Question

In 10 years, A will be twice as old as B was 10 years ago, if A is now 9 years older than B, the present age of B is?

Answer 1

let a age=x
let b age=y
10+x=2(y-10)
10+x=2y-20
2y-x=30

x=9+y

s0
2y-9-y=30
y=39

x=48