Remark
There are many ways you can set up the problem. The conventional way is to set up a % equation
Givens
Let x = the number in the entire class.
Let 80% of the class = 24
Argument
80% of x = 24 Change 80% to a fraction.
80/100 * x = 24 Divide by 100
0.8 x = 24 Divide by 0.8
x = 24 / 0.8
x = 30
There were 30 people in the class.