We can solve this problem by using two proportions. The first proportion will be the percent we are looking for: 20% or 20/100.

The second proportion will have the number we are looking for, or N, as a numerator and the whole number 90 as a denominator: N/90
To solve the problem, we cross multiply.

15% of the members of the football team play both offense and defense. The Spartans have 60 players on their squad.

How many players play both offense and defense?

The first proportion we use is 20% or 20/100. The second proportion will have the whole number 90 as a numerator and the number we are looking for, or N, as the denominator.


To solve the problem, we cross multiply.
20 x N = 90 x 100
20N = 9000
N = 450
Therefore the number we are looking for is 450.

  writer:Kevin Gallagher