Question

Frank tried to solve an equation step by step.

\[\qquad\begin{aligned}
-5&=5(d+4)\\\\
\\
-5&=5d+20&\green{\text{Step } 1}\\\\
\\
15&=5d&\blue{\text{Step } 2}\\\\
\\
3&=d&\purple{\text{Step } 3}\\\\
\end{aligned}\]
Find Frank's mistake.
Choose 1 answer:
A
\[\green{\text{Step }1}\]
B
\[\blue{\text{Step }2}\]
C
\[\purple{\text{Step }3}\]
D
Frank did not make a mistake.

Answer 1

B

From -5 = 5d + 20, subtracting 20 gives -25 = 5d, not 15 = 5d. Thus Step 2 is incorrect.