Problem
First name
Kira and Emma
School
Wycombe High School
Country
Age
13
(15+5+x)/3 = (x+7+9+17)/4
(20+x)/3 = (x+33)/4
(80+4x)/12 = (3x+99)/3
80+4x = 3x+99
7x = 179
x = 19