Answer:
the value you are solving for over total value.
Explanation:
The way I learned it was like this:
Let's say you're trying to find the percent of red marbles there are in a pile. You have 24 red marbles and there are 48 in all. Set it up like so:

x is over 100 because all percents are out of 100, and 24 is over 48 because that's the value you are trying to solve the percent for. Then cross-multiply.

Then divide.
÷
÷


So the percentage is fifty.