In order to find what percentage one number is of the other you divide the first by the second.
For example 91/524 = 0.1682070240295749
Now we divide that number by 100 to make it a percentage (more on that in a minute); 16.82070240295749%
Then we simplify to get; 17% or 16.8% depending on how specific you want to be.
If your curious why we divide by one hundred look at this, per-cent, cent means hundred; percent can mean per hundred. About 17 out of every hundred students attended the math class.
