Question

A system of equations is shown below: Equation A: 4c = d − 8 Equation B: c = 5d + 8 Which of the following steps should be performed to eliminate variable d first?
A. Multiply equation B by 4
B. Multiply equation A by -5
C. Multiply equation A by 4
D. Multiply equation B by 5

Answer 1

Equation A: 4c = d − 8
Equation B: c = 5d + 8 

Multiply Equation A by -5:
Equation A: - 20c = -5d + 40

Equation (1) + (2) :
-19c = 48

Answer: B. Multiply equation A by -5