In a fixed time, a boy swims double the distance along the current
that he swims against the current. If the speed of the current is 3 kmph then what is the speed of the boy in still water?

A) the speed of the current; y = 3 kmph

the speed of the current; X = ?

time = constant

Downstream speed; X + 3 

Upstream speed; X – 3

How to proceed from here?