Question

In a certain class, 15% of the class failed a math test completely, 25% students made one mistake each, and 24 students got a perfect score. How many students are in this class?

Answer 1

There are 40 students in the class.
15 % + 25 % =  40%
So 24 must be equal to the remaining 60% and 24 is 60% of 40.
Hope it helps!