Lina is 4 years older than christy, five years from now , her age will be twice Christy's age 4 years ago. What are their present ages?

Answer 1

Christy ---- x
Lina -------x+4

Five years from now:
Lina -------x + 9

Four years ago:
Christy --- x-4

x+9 = 2(x-4)
x+9 = 2x - 8
x = 17

Christy is 17 and Lina is 21

check:
five years from now Lina 26
Four years ago Christy was 13
is Lina age twice that of Christy ? YES