Question 4216
Use S for the unknown age of the son:

In 2000:
Son: S
John: 11*S <font size="-1">(11 times son's age)</font>

12 Years Later:
Son: S + 12
John: 3(S+12) <font size="-1">(3 times his sons age now)</font> or (11*S)+12 <font size="-1">(12 years older than in 2000)</font>

3(S+12) is equal to 3*S + 3*12 because of the distributive property.
3*S + 36 = 11*S + 12
Subtract 12 from each side so it becomes:
3*S + 24 = 11*S
Now subtract 3*S from each side so it becomes:
24 = 8*S
Divide each side by 8:
3 = S

In 2000, the son is 3 and the father is 33.
In 2012, the son is 15 and the father is 45.

Check:
3*11=33
3+12=15
15*3=45
33+12=45<p><marquee behavior="alternate">Solved By: NtNk</marquee>