Add new question to FAQ

Tighten language on some FAQ answers

FAQ.md

@@ -16,8 +16,9 @@ Alternatively, you could [contribute](#CONTRIBUTING.md) an answer yourself.
 - [Why doesn't the curriculum cover/ignore topic X?](#why-doesnt-the-curriculum-coverignore-topic-x)
 - [Why is the curriculum missing some pre-requisites?](#why-is-the-curriculum-missing-some-pre-requisites)
 - [Why is the Firebase OSSU app different/broken?](#why-is-the-firebase-ossu-app-different-or-broken)
-- [What is a good course to learn the language XXXX?](#what-is-a-good-course-to-learn-this-particular-language)
+- [What is a good course to learn the language XXXX?](#what-is-a-good-course-to-learn-a-particular-language)
 - [Why require experience with a sizable project before the Software Engineering courses?](#why-require-experience-with-a-sizable-project-before-the-Software-Engineering-courses)
+- [How can I review the math prerequisites?](#how-can-i-review-the-math-prerequisites)
 
 ## Questions
 
@@ -46,16 +47,13 @@ When attempting to enroll in such a course:
 
 ### Does every resource in the main curriculum have to be free?
 
-Yes, because we have to draw a line.
-As soon as we require paid resources in the main curriculum, we might as well tell people to pay half a million dollars to attend a university.
-We are an Internet-based community of learners, not a business, so free is the most sensible price and ensures that the only price you need pay is the price of Internet access.
+Yes, that is a core goal of OSSU.
 
-At the same time, we recognize that education is a scarce resource and therefore requires payment to instructors to make it sustainable in the long term.
+At the same time, we recognize that education is a resource that requires payment to instructors to make it sustainable in the long term.
 Therefore, we respect the business model of websites like edX, which make their materials free but with some paid add-ons, like official certificates or extra interaction with course instructors.
 
 So we only require that the *learning materials* of a resource be free to access, not that every possible add-on be free.
 It would be ideal if graded assignments were always free but if we had this requirement, we would have to exclude any resource that doesn't have graded assignments at all.
-Plus, there are other ways to get feedback on your work, and OSSU is a do-it-yourself education.
 
 ### In what order should I take the courses?
 
@@ -99,7 +97,7 @@ The curriculum assumes two things:
 - You have gotten through a standard high school curriculum that included physics and pre-calculus.
 
 Without these assumptions, the curriculum would be out of control with trying to fill in your knowledge gaps.
-But those who for whatever reason didn't get all the way through high school math and physics are in luck: you can find the content you need on [Khan Academy](https://www.khanacademy.org/).
+For those who want to study math pre-requisites, read more [here](#how-can-i-review-the-math-prerequisites)
 
 Of course, if you find that the curriculum is missing a pre-requisite for a course that isn't part of a normal high school curriculum, please let us know!
 
@@ -111,7 +109,7 @@ Unfortunately, the app has not been updated in many years. It does not reflect u
 
 It is our hope that the creators of the Firebase app can bring the app up to date. Until that time, the firebase app should be considered a deprecated product that is no longer supported.
 
-### What is a good course to learn this particular language?
+### What is a good course to learn a particular language?
 OSSU focuses on finding the best courses to learn computer science topics, and isn’t focused on finding language specific courses. If you are looking to learn a particular language or framework there are two great resources to check.
 1. [Hackr.io](https://hackr.io/) allows users to submit and upvote learning resources for topics such as Python or the Java Spring Framework.
 2. Most languages have a community on reddit. When you find the community’s page, check to see if there is a wiki or sidebar with resources. For example, see [/r/python](https://old.reddit.com/r/Python). Note that the sidebar content can be different depending on whether you use www.reddit.com or old.reddit.com.
@@ -119,4 +117,17 @@ OSSU focuses on finding the best courses to learn computer science topics, and i
 ### Why require experience with a sizable project before the Software Engineering courses?
 Software engineering tries to solve the problem of dealing with large programs. Building a sizable program before taking the SE courses will help you understand what SE is trying to solve. We recommend the Jack-to-VM-code compiler project from the nand2tetris course because it's the first project in the curriculum that is complex enough to see value in a SE course. That said, any sizable project will do and can come from outside of the OSSU curriculum. The idea is that you've done some large enough project where the pieces started to feel unmanageable. This experience will expose pain points and lead to a better understanding of SE.
 
+### How can I review the math prerequisites?
+Many OSSU students choose to review math topics that they have not studied recently.
+OSSU recommends students use Khan Academy for such a review.
+Below are links to topic assessments.
+After taking an assessment, you should have a clear idea what topics to study, and resources on Khan Academy to use.
 
+- [Arithmetics](https://www.khanacademy.org/math/arithmetic#arithmetic-subject-challenge)
+- [Basic Geometry](https://www.khanacademy.org/math/basic-geo#basic-geo-subject-challenge)
+- [Pre-algebra](https://www.khanacademy.org/math/pre-algebra#pre-algebra-subject-challenge)
+- [High School Math 1](https://www.khanacademy.org/math/math1#math1-subject-challenge)
+- [High School Math 2](https://www.khanacademy.org/math/math2#math2-subject-challenge)
+- [High School Math 3](https://www.khanacademy.org/math/math3#math3-subject-challenge)
+
+(Math 1, 2, 3 covers all of algebra, pre-calculus, high school geometry, trig, stats. It interleaves the order of these topics.)