I can't figure this out.

There are three boys consecutive even aged. The product of the first and third boy is 20 more than twice the first
What are there ages?

just write out all the equations and solve. I assume "consecutive even aged" means something like 10 12 14
call the three ages a b and c
a<b<c
b=a+2
c=b+2
a*c=20+2*a

Do some substitution and solving and you're done!