Question

There are as many girls as there are boys in a class. 8 girls went for a dance competition. now there are twice as many boys as there are girls in the class. how many students were there in the class initially?

Answer 1

Let the number of girls be x and the number of boys be y

The number of boys is the same as the number of girls.
x = y 
The number of boys is twice the number of girls when 8 girls left.
2(x - 8) = y


x = y ---------------- (1)
2(x - 8) = y -------- (2)

Sub (1) into (2)

2(y - 8) = y
2y - 16 = y
2y - y = 16
y = 16
There were 16 boys and 16 girls initially.

16 + 16 = 32 
There were a total of 32 students in the class initially.