13.066. At a machine-building plant, a new type of parts for generators has been developed. From 875 kg of metal, they now produce three more new-type parts than old-type parts were produced from 900 kg. What is the mass of the new and old type parts, if two new-type parts are 0.1 tons lighter than one old-type part?
## Solution.

Let $x$ kg be the mass of the new type of part, and $y$ kg be the mass of the old type. According to the problem, $y-2 x=100$. From 875 kg, $\frac{875}{x}$ new type parts are made, and from 900 kg, $\frac{900}{y}$ old type parts were made. According to the problem, $\frac{875}{x}-\frac{900}{y}=3$. Solving the system $\left\{\begin{array}{l}\frac{875}{x}-\frac{900}{y}=3, \\ y-2 x=100,\end{array}\right.$ we find $x=175$ kg, $y=450$ kg.

Answer: 175 and 450 kg.