13.250. A brigade of lumberjacks was supposed to prepare $216 \mathrm{~m}^{3}$ of wood over several days according to the plan. For the first three days, the brigade met the daily planned quota, and then each day they prepared 8 m $^{3}$ more than planned, so by the day before the deadline, they had prepared 232 m $^{3}$ of wood. How many cubic meters of wood per day was the brigade supposed to prepare according to the plan?
Solution.

Let the team be supposed to prepare $x$ m ${ }^{3}$ of wood per day and should have worked $\frac{216}{x}$ days. In the first 3 days, they prepared $3 x \mathrm{~m}^{3}$, and for the remaining days, they prepared $(x+8)\left(\frac{216}{x}-4\right)$.

According to the condition, $3 x+(x+8)\left(\frac{216}{x}-4\right)=232$, from which $x=24 \mathrm{~m}^{3}$.

Answer: $24 \mathrm{~m}^{3}$.