Can someone help solve, 3y+6=30-7y

What properties allow transformation to be used as a problem solving tool

In the given triangle, ∠aed ∼ ∠ abc, ad = 6.9, ae = 7.2, de = 5.2, and bc = 10.2. find the measure of bd and ce. round your answer to the nearest tenth.

Construct the graph that models the given situation