13.059. On both sides of a 1200 m long street, there are rectangular strips of land allocated for plots, one being 50 m wide, and the other 60 m wide. How many plots is the entire village divided into, if the narrower strip contains 5 more plots than the wider one, given that each plot on the narrower strip is 1200 m$^{2}$ smaller than each plot on the wider strip?
## Solution.

Let $x$ be the number of plots on the wide strip, $x+5$ plots - on the narrow strip, $y$ m - the width of a plot on the narrow strip, and $y+1200$ m - on the wide strip. According to the problem, $\left\{\begin{array}{l}(x+5) y=1200 \cdot 50, \\ x(y+1200)=1200 \cdot 60 .\end{array}\right.$ Solving the system, we find $x=20$ plots on the wide strip. Therefore, on the narrow strip, there are 25 plots. In total, $20+25=$ $=45$ plots.

Answer: 45.