Question

How to do do this question I don't know how to do

Answer 1

Hello,

Let denote
h the number of men in the concert hall (before leaving)
f the number of women in the concert hall (before leaving)

1/5 h quit =60/2
15/100 f =60/2

h=30*5=150
f=30*100/15=200

Tey were 150+200 = 350 humans in the hall.
(why h : homme, f:femme you may call m and w)