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Complete the solution of the equation. find the value of y when x equals to 28 x+3y=28

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.]

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25