Answer
Find out the how many women were there .
To prove
Let us assume that the x is the scalar multiple of men and women.
As given
The ratio of men to women was 3 : 2.
Than
The total number of men = 3x
The total number of women = 2x
As given
If 120 men used the gym.
thus
120 = 3x
x = 40
The total number of women = 2 × 40
= 80
Therefore 80 women were there in the gym .