Find the average number of boys in school A and
C.

Let the number of teachers in school A = 5x Then the number of boys in school A = 7x According to the question, => 5x + 7x = 84 × 2 => x = 14 So, number of teachers in school A = 5 × 14 = 70 Number of boys in school A = 7 × 14 = 98 Number of girls in school B = 84 × (9/7) = 108 Number of girls in school C = 140 – 108 = 32 Number of boys in school C = 98 + 2 = 100 Number of teachers in school B = 168 × (13/24) = 91 Number of boys in school B = 168 – 91 = 77 Number of teachers in school C = 91 + 11 = 102 Number of boys in school C = 98 + 2 = 100 Required average = (98 + 100)/2 = 99