I don't get page 50 of algebra with pizzazz!

Question

Please help?
7) Kathy is 6 years younger than bill. 12 years ago bill was twice as old as Kathy was then. How old are they now?

Answer 1

let Bill's present age be x
then Kathy's present age is x-6

12 years ago:
Bill was x-12
Kathy was x-6 - 12 or x - 18

at that time bill was twice as old as Kathy --- x-12 = 2(x-18)

x-12 = 2x - 36
-x = -24
x = 24

so now bill is 24 and Kathy is 18

Answer 2

Alright thanks I get it now (:
I guess I was just multiplying wrong.