3/4 of the girls in a 3rd form class play netball and 4/7 play volleyball . Every girl plays atleast one of these games. If 27 play both games,how many girls are there in the 3rd form

Answer 1

let the total be x

make a Venn diagram of two intersecting circles, and place 27 in the intersection.
In the exclusive parts of the two circles place
(3/4)x - 27 and (4/7)x - 27

then:

(3/4)x-27 + 27 + (4/7)x-27 = x
(3/4)x + (4/7)x-27 = x
multiply each term by 28, the LCD
21x + 16x - 756 = 28x
9x=756
x = 84

Answer 2

THE 20 boy