Answer :


you substitute 5y+41 for x and get 5y+41+3y=-15 then you simplify by doing 8y+41=-51 subtract 41 from each side and divide by 8 to get y alone. That's how you get 11.5 for your answer.
Panoyin
x = 5y + 41
x + 3y = -15

(5y + 41) + 3y = -15
(5y + 3y) + 41 = -15
          8y + 41 = -15
                - 41   - 41
                  8y = -56   
                   8       8
                    y = -7
x = 5(-7) + 41
x = -35 + 41
x = 6
(x, y) = (6, -7)