Question

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

Answer 1

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