What is the value of (a + b) in the system of equations below?

8 (a + b) + 3z = - 9

a + b + z = 2

Select one:

A. - 5

B. - 4

C. - 3

D. - 2

C

given the 2 equations

8 (a + b) + 3z = - 9 → (1)

(a + b) + z = 2 → (2)

multiply (2) by 3 so that the coefficients of z are equal

3 (a + b) + 3z = 6 → (3)

subtract (1) - (3) to eliminate term in z

5 (a + b) = - 15 (divide both sides by 5)

(a + b) = - 3 → C