Solve each system by substitution

5x + 7y = - 23

Y = - 2x - 11

x = - 6

Explanation:

5x + 7y = - 23

Y = - 2x - 11

Substitute - 2x - 11 for y in 5x + 7y = - 23

5x + 7 (-2x - 11) = - 23

Simplify both sides of the equation

5x + 7 (-2x - 11) = - 23

5x + (7) (-2x) + (7) (-11) = - 23 (Distribute)

5x + - 14x + - 77 = - 23

(5x + - 14x) + (-77) = - 23 (Combine Like Terms)

-9x + - 77 = - 23

-9x - 77 = - 23

Add 77 to both sides

-9x - 77 + 77 = - 23 + 77

-9x = 54

Divide both sides by - 9

-9x / - 9 = 54 / - 9

x = - 6