Question

Ralphie has a large tropical fish collection. He gives 2/3 of his fish to a local high school. Then he gives 2/5 of the remaining fish to an elementary school. In the end he has 30 fish left. How many did he have at first?

Answer 1

Let initially number of fishes =x

He gives 2/3 of his fish to a local high school, that is he gives 2x/3 fish .

So number of fishes left = x -(2x/3) = x/3 . And he gives 2/5 of x/3 to an elementary school , that is , he gives 2x/15 fishes to the elementary school. And finally the number of fishes left =30 , that is

$x-(\frac{2x}{3}+\frac{2x}{15})=30$

$x-\frac{12x}{15}=30$

$\frac{3x}{15}=30$

$x = 150$

So initially he have 150 fishes .