Efrain is setting posts in the ground for a fence and wants to make sure the post and level ground make a right triangle. He doesn't have a level, so instead he ties a string to the top of the post and attaches the other end to the ground using a big nail and makes measurements as shown in the diagram. How can he use his measurements to determine if the post and ground are at right angles?

Select the correct answer from each drop-down menu. a system of equations and its solution are given below. system a complete the sentences to explain what steps were followed to obtain the system of equations below. system b to get system b, the equation in system a was replaced by the sum of that equation and times the equation. the solution to system b the same as the solution to system a.]