solution is (x, y ) → (- 4, - 4 )
- 3x + 7y = - 16 → (1)
- 9x + 5y = 16 → (2)
multiply all terms in ( 1) by - 3. This will make the x-terms cancel out in the next step
9x - 21y = 48 → (3)
add (2) and (3) term by term to eliminate x
(- 9x + 9x ) + (5y - 21y ) = (16 + 48)
- 16y = 64 ( divide both sides by - 16 )
y = - 4
substitute y = - 4 into (1) or (2) and solve for x
(2) → - 9x - 20 = 16 ( add 20 to both sides )
- 9x = 36 ( divide both sides by - 9 )
x = - 4
solution is (x, y) → (- 4, - 4)
