Which part of the angle is the vertex?

Linda loans her friend $250 with a 5% monthly intrest rate. how much was the whole loan?

3/4 = c/36 i need with this fraction proble.

If you were constructing a triangular frame, and you had wood in the length of 4inches, 4 inches, and 7 inches, would it make a triangle? would you be able to create a frame from these pieces of wood?