Question

22 children were at a birthday party. Each girl drank 2 glasses of fruit punch and each boy drank
3 glasses of fruit punch. If the boys drank 31 more glasses of fruit punch, how many girls attended
the party?

Answer 1

let no. of guys = x
and no of girls = y
equations formed:
x + y = 22 ----1
2y + 31 = 3x----2

on solving simultaneously,
x = 15, y = 7

Answer 2

no of girls at the party=a
no of boys at the party=b
no of glasses the girls drank=2a
no of glasses the boys drank=3b
3b-2a=31-----------(1)    ======>3b-2a=31
a+b=22-------------(2)  *2======>2b+2a=44
_______________                        _________
=========================>5b=75=====>b=15
in equation 2
a+15=22
a=7
.'. no of boys=15
no of girls=7