15. (6 points) The poetry lecture lasted for 2 hours $m$ minutes, and at the end, the positions of the hour and minute hands on the clock were exactly swapped compared to when it started. If $[x]$ represents the integer part of the decimal number $x$, then $[m]=$ $\qquad$ .
【Answer】Solution: According to the problem, we know:
The sum of the distances traveled by the hour hand and the minute hand is 3 laps, $3 \times 60 \div\left(1+\frac{1}{12}\right)=\frac{180 \times 12}{13}=166 \frac{2}{13}$. 166 minutes is 2 hours and 46 minutes.

Therefore, the answer is: 46