Some of the questions on the ACT Math test deal with pre-algebra and algebra problems. There are only a few formulas to remember, but they are vital.

Here are two important pre-algebra formulas you need to know:

Here are three useful algebra formulas:

• Direct proportionality. Two variables, x and y, are directly proportional when the following equation is true for some constant k:

• Inverse proportionality. Two variables, x and y, are inversely proportional when the following equation is true for some constant k:

• The quadratic formula. For any quadratic equation — that is, an equation of the form ax2 + bx + c = 0 — the value of x is as follows: