# High-school algebra: A Khan Academy revision guide

(under construction ... abandoned until I have students who need this again ...)

If you have the high-school algebra skills, then all the rest of high-school math is much easier. For example, high-school probability is just algebra plus counting. High-school geometry is algebra plus some basic formulas about shapes. Calculus is just algebra plus one or two handful of new rules. Etc

In the spirit of these revision guides, let us start with the most important skill. If you can do this, everything else should not be hard any more.

[Solving Systems of Equations](https://www.khanacademy.org/math/algebra-basics/alg-basics-systems-of-equations/alg-basics-elimination-method-systems/e/systems_of_equations_with_elimination)

An easier version of this is if there is only one unknown.

[Solving Equations with One Unknown](https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-solving-equations/equations-with-parentheses/e/multi-step-equations-rational)

In order to be able to do these exercises, you need to know things like $3-(4-3)= 3-4+3$. This can be practiced here

[Adding and Substraction Negative Numbers](https://www.khanacademy.org/math/pre-algebra/pre-algebra-negative-numbers/pre-algebra-add-and-sub-integersss/e/integer-addition-and-subtraction-2?modal=1)

And of course, one needs to know about fractions.

[Fractions Unit Test](https://www.khanacademy.org/math/pre-algebra/pre-algebra-fractions/test/pre-algebra-fractions-unit-test?modal=1)

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