So we have 30 times some number is equal to 100. You could say 30 × ? = 100, or in a more math-y way,

, where x is the number we're trying to find (not to be confused with the times sign). To find x, we need to isolate it (get it alone).
For

, we divide both sides of the equation by 30.

On the left side, the 30's cancel, so we get

, but we're not done. We need to simplify this fraction.
We can rewrite the fraction with common factors in mind, like

.
With more practice, this will seem more automatic to you.
This fraction is now in simplest form, so our final answer is
