Five, a factory has 350 tons of coal in stock, planning to burn it all within a certain number of days. Due to improvements in the boiler, 2 tons are saved each day, allowing the stock of coal to last 15 days longer than originally planned, with 25 tons remaining. How many tons of coal were originally planned to be burned each day? (10 points)
Five, Solution: Let the original plan be to burn $x$ tons of coal per day, then the actual daily consumption is $(x-2)$ tons.
$$
\frac{350-25}{x-2}-\frac{350}{x}=15 \text {. }
$$

Simplifying, we get $3 x^{2}-x-140=0$.
Solving, we get $\mathrm{x}_{1}=7, \mathrm{x}_{2}=-\frac{20}{3}$.
Upon verification, $\mathrm{x}_{1}, \mathrm{x}_{2}$ are both roots of the original equation, but $\mathrm{x}_{2}=-\frac{20}{3}$ is not feasible and is discarded.
Answer: The original plan was to burn 7 tons of coal per day.