A student showed work to solve the equation 3(2d +1) – 39 = 9d + 6 for d.
3(2d + 1) – 39 = 9d + 6
Step One 6d + 3 – 39 = 9d + 6
Step Two 6d – 36 = 9d + 6
Step Three –36 = 3d + 6
Step Four –30 = 3d
Step Five –10 = d
The student made a mistake in Step Four. Choose the correct equation for Step Four.
A. –42 = 3d
B. –36 = 9d
C. –6 = 3d
D. –12 = 6d
