How to do percentages?

Say you're trying to figure out what percentage 3 is of 15.

3/15 = x/100

You would cross multiply so ...

3 (100) = 15x

Then simplify.

300 = 15x

300/15 = 15x/15

20 = x

Therefore, 3 is 20% of 15.

How to calculate percentages:

First, work out the difference between (increase) the two numbers you're comparing.

*Increase = New number - Original number*

Then, divide the increase by the original number and multiply the answer by 100.

*% increase = Increase divided by the Original number times 100.*

If your answer is a negative number than it is a percentage decrease. (You'd pretty much have to do the same thing that you do for the percentage increase except you'd get a positive number.)