Question

There are 28 students in Mr. Flynn’s class. The ratio of his students who are in the play to those who are not in the play is 2:5.

Answer 1

8 students in the play, 20 are not

Answer 2

Let the number of students who are in the play be 'x'

Total number of students = 28

So number of students who are not in the play are 28 - x

The ratio of number of student in a play to the number of students not in the play = 2 : 5

$\frac{x}{28 - x} = \frac{2}{5}$

Cross multiply

5x = 2(28 - x)

5x = 56 - 2x

Add + 2x on both sides, we get

5x + 2x = 56 - 2x + 2x

7x = 56

Divide both side by 7, to find x

$\frac{7x}{7} = \frac{56}{7}$

x = 8

So number of students who are in the play = 8

And number of students who are not in the play = 28 - x = 28- 8 = 20