Task 1. One painter paints $1 \mathrm{~m}^{2}$ in 35 minutes, and another painter paints $1 \mathrm{~m}^{2}$ in 42 minutes. The painters start together to paint two identical buildings (with the same areas). After the first one finishes, the second one still has $52 \mathrm{~m}^{2}$ left to paint. What is the area of the buildings.
Solution. Let the buildings have an area of $x \mathrm{~m}^{2}$. The conditions of the problem give the equation $35 x=42(x-52)$, from which we get $x=312 \mathrm{~m}^{2}$