Hank made a mistake in Step 1 of his work.
The original equation is:
\[ 25 = \frac{x}{4} - 9 \]
To isolate \(\frac{x}{4}\), you need to add 9 to both sides:
\[ 25 + 9 = \frac{x}{4} \] \[ 34 = \frac{x}{4} \]
So the correct equation should be:
\[ 34 = \frac{x}{4} \]
Hank incorrectly wrote this as \(16 = \frac{x}{4}\) in Step 1.
Thus, the mistake is that he miscalculated the left side of the equation after adding 9 and incorrectly resulted in \(16\) instead of \(34\).
Then, in Step 2, Hank similarly made an error based on his incorrect Step 1 when he multiplied both sides by 4 to find \(x\):
With the incorrect equation \(16 = \frac{x}{4}\), multiplying both sides by 4 gives:
\[ x = 64 \]
However, the correct calculation using \(34 = \frac{x}{4}\) would give:
\[ x = 34 \times 4 = 136 \]
So, the correct value of \(x\) should be 136, not 64.