14. (15 points) There are two plots of land, with an average grain yield of 675 kilograms per mu. The first plot is 5 mu, with a grain yield of 705 kilograms per mu. If the second plot has a grain yield of 650 kilograms per mu, how many mu is the second plot?
【Analysis】Assuming the average yield per mu of the two plots of land is 675 kilograms, then the first plot has overestimated the yield per mu by $705-675=30$ kilograms, and 5 mu overestimated by $30 \times 5=150$ kilograms. The actual average yield per mu of the two plots is $675-650=25$ kilograms more than the average yield per mu of the second plot, so the second plot has $150 \div 25=6$ mu. According to this, the solution can be found.

【Solution】Solution: Assuming the average yield per mu of the two plots of land is 675 kilograms,
$$
\begin{aligned}
& (705-675) \times 5 \div(675-650) \\
= & 150 \div 25 \\
= & 6 \text { (mu) }
\end{aligned}
$$

Answer: The second plot of land has 6 mu.