Question

Solve the system of equations: 10x + 7y = 49 and 10y – x = 70

Answer 1

10x + 7y = 49
10y – x = 70 so x = 10y - 70

substitute x = 10y - 70 into 10x + 7y = 49
10x + 7y = 49
10(10y - 70) + 7y = 49
100y - 700 + 7y = 49
107y = 749
      y = 7

x = 10y - 70 = 10(7) - 70 = 0

answer
(0, 7)

hope it helps