13.150. In the manuscript of an arithmetic problem book, an example was written in which a given number had to be multiplied by 3 and 4 subtracted from the result. In the printing house, a misprint was made: instead of the multiplication sign, a division sign was placed, and instead of a minus sign, a plus sign. Nevertheless, the final result did not change. What example was intended to be placed in the problem book?
## Solution.

Let $x$ be the given number. Then the assumed example is $-3 x-4$, and the printed one is $-\frac{x}{3}+4$. According to the condition, $3 x-4=\frac{x}{3}+4$, from which $x=3$.

Answer: $3 \cdot 3-4$.