Question

{2y =8x+6

9x+3y=21

Answer 1

well, if 2 y = 8 x + 6

then y = 4 x + 3
so use that
9 x + 3 ( 4 x + 3 ) = 21

9 x + 12 x + 9 = 21
Now solve that for x and go back and get y.