Are these triangles similar? if so how? if not, explain.

What is the solution to the system of the equations? x = y - 3 x + 3y = 13

Ican figure out 20 shares multiply by $117.98 =2359.6920 shares multiply by $124.32=2486.40then take 40 shares multiply by $128.48=5139.20after that i'm lost any be greatly appreciated.

To prove that def ~ gfh by the sss similarity theorem using the information provided in the diagram, it would be enough additional information to know that