Number of children from an after school that went to the martinee = 40
Percentage of children from an after school that went to the martinee = 25%
Let us assume the number of children in the club = x
Then
25% * x = 40
(25x/100) = 40
x/4 = 40
x = 40 * 4
= 160
So the total number of children in the club is 160. I hope the procedure is clear enough for you to understand. you can always use this method for solving similar problems without requiring any help from outside.