13.165. There are 140 cans of two capacities. The volume of the larger can is 2.5 liters more than the volume of the smaller can. The total volume of the larger cans is equal to the total volume of the smaller cans and is 60 liters. Determine the number of large and small cans.
## Solution.

Let $x$ be the number of large jars, $(140-x)$ be the number of small jars, $y$ liters be the volume of the smaller jar, and $(y+2.5)$ liters be the volume of the larger jar. According to the problem, $\left\{\begin{array}{l}x(y+2.5)=60, \\ (140-x) y=60,\end{array}\right.$ from which $x=20$ is the number of large jars and $140-20=120$ small jars.

Answer: 20 and 120.