In all math courses in high school including advanced functions and vectors and calculus you need to know how to solve a linear equation.
A linear equation is an equation of form ax+b=c. Here, a, b and c are number and x is our unknown. In order to find x we move b to the other side so we have ax=c-b, now we divide both sides by a, so . Let see an example:
To solve this we move 1 to the other side, so 2x=8-1=7 and the we divide both sides by 2. Then we have x=7/2 =3.5