Question

Larry is 8 years older than his sister. In 3 years, he will be twice as old as she is now. How old are they now?

Answer 1

Let Sister's age now = s  

So Larry is now s + 8  

In THREE Years Sister = s + 3  

Larry = {s + 8} + 3  

But We are told that he will be TWICE as old as Sister is NOW!!!  

So s + 11 = {2s}  

Solve s = 11  

So Sister is ELEVEN Years old and Larry is NINETEEN Years old.

Answer 2

Lets say that Larry's sister is x

Then Larry is x+8

In 3 years Larry will be x+11 or 2(x+3)

So x+11=2(x+3)

x+11=2x+6

x=5

Larry is 13, his sister is 5