Answer
The second step is wrong.
Work Step by Step
The given equation is
$10=ax-3b$
Add $3b$ to each side.
$10+3b=ax-3b+3b$
Simplify.
$10+3b=ax$
Divide each side by $a$.
$\frac{10+3b}{a}=\frac{ax}{a}$
Simplify.
$\frac{10+3b}{a}=x$
Hence, the second step is wrong.
