Substitute - 4*+y=6, - 5*-y=21

(x, y) = ( - 3, - 6)

Step-by-step explanation:

given the 2 equations

- 4x + y = 6 → (1)

- 5x - y = 21 → (2)

rearrange equation (1) expressing y in terms of x

y = 6 + 4x → (3)

Substitute y = 6 + 4x into equation (2)

- 5x - (6 + 4x) = 21

- 5x - 6 - 4x = 21

- 9x - 6 = 21 (add 6 to both sides)

- 9x = 27 (divide both sides by - 9)

x = - 3

Substitute x = - 3 into (3)

y = 6 - 12 = - 6

solution is ( - 3, - 6)