Please help me find the missing variable on the right triangles with step by step work!!

David must install fencing around a lot that is shaped like a right angle.the side of lot that runs east-west is 200 ft long.the side of the lot runs north-south is 125 ft long.calculate how many feet of fencing he will need to surround the entire lot.

Triangle xyz has vertices x(1,3), y(0,0)

Use the elimination method to solve the systems of equations.choose the correct ordered pair. 7x+4y=39