How to use properties to find the sum or product for 8×51

How do i do this? i don’t understand

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.]

How do you write a paragraph proof to prove that the corresponding angles shown are congruent