You may want to review multiplying fractions first.
Exponents are another word for raising something to a power. They look like “(−5 ⁄ 2)2”. As I hope you already know, this means you multiply −5 ⁄ 2 by itself and get 25 ⁄ 4.
It gets harder when the base (the big number on the bottom) can be a letter. There are three rules you need to remember. For this section, though, you'll only need one of them. It says that if you're multiplying two powers with the same base, the exponents (the little numbers up top) add. For example, x4x6 = x10. Dividing goes the other way around, so x6 / x4 = x2.
What happens if you have to divide x4 / x6? You use the same rule as before, getting x−2. This means the same thing as 1 ⁄ x2.
Note that powers with different bases don't combine. So if you want to multiply 3x4y by 2x5y2, we multiply the numbers in front (getting 6), add the exponents on the x's (getting 9) and add the exponents on the y's (getting 3 — remember that y is the same thing as y1). The answer is then 6x9y3.
Finally, note that anything to the 0 power is 1. So x3 / x3 = x0 = 1.