Find Area of Similar Right Triangle

Question

Need help to approach following from GRE study guide

Here is what I have so far

$area = 1/2 bh$

$area CDE = 1/2 bh = 42 = 21 bh$

$AD = 3CD$

Honestly, I'm not sure how to approach. Please give hints.

Answer 1

As triangles $CDE$ and $ADG$ are similar, and you are given that $AD=3CD$, what can you say about the relationship between sides $AG$ and $CE$, and between sides $DG$ and $DE$?

Answer 2

HINT:

I would say, split image: