Eureka is 16 years younger than Renton. In 13 years Renton will be twice as old as Eureka. How old are they now?

Now:

Renton --- x
Eurekd --- x -16

13 years from now:
Renton= x+13
Eureka = x-16 + 13 = x - 3

x+13 = 2(x-3)
x+13 = 2x - 6
-x = -19
x = 19

Renton is now 19
Eureka is now 3

check:
in 13 years from now,
Renton will be 32
Eureka will be 16 , so Renton will be twice as old