Let the number of girls = x (say) and the number of boys = y (say) then total students =
x + y -10 …………… (1)
and also
The number of girls = number of boys + 4
x = y + 4 …………….(2)
Put this ‘x’ value in equation (1), we get
y + 4 + y = 10
⇒ 2y + 4 = 10
⇒ 2y = 10 – 4 = 6
∴ y = 6/2 = 3
So y = 3 then
x + y = 10 becomes
x + 3 = 10
⇒ x = 10-3
∴ x = 7
So the number of girls = 7 and the number of boys = 3.