## Task A-1.1.

In the lake, there live red and yellow fish. Two fifths of the total number of fish are yellow, and the rest are red. Three quarters of the yellow fish are females. If it is known that the total number of females is equal to the total number of males in the lake, what is the proportion of red males among all the fish in the lake?
## First solution.

The proportion of yellow male fish among all fish is $\frac{2}{5} \cdot \frac{1}{4}=\frac{1}{10}$.

Therefore, the proportion of red male fish is $\frac{1}{2}-\frac{1}{10}=\frac{2}{5}$.