Translation:

    G + 6 = 2A

Now let's put those two equations together:

    A = G + 2
    G + 6 = 2A

Now since A = G + 2, we can substitute (G + 2) for A
in the second equation:

    G + 6 = 2(G + 2)

See if you can solve that equation for G.  If you can't,
email me back.  If you can, take what you get, then 
substitute it for G in 

     A = G + 2

to find A's age now, and then since the question is

you will add 6 to their ages.

Edwin