Task 1. Today, Vovochka started watching anime. If he watches 2 episodes per day, by April 1, 2023 (not inclusive), he will have 215 episodes left unwatched. If he starts watching 5 episodes per day, he will have only 50 left. What is the date today and how many episodes are in the series?
Answer: February 5, 2023, 325 episodes.

Solution. Let there be $n$ days left until April 1, and $N$ episodes in the anime. Then, according to the condition, $N-2n=215$ and $N-5n=50$. Subtracting the second equation from the first, we get $3n=215-50=165$, that is, $n=55$.

(We can also solve this without introducing variables. By increasing the viewing intensity by 3 episodes per day, Vovochka will watch $215-50=165$ extra episodes, which means it will take $165 / 3=55$ days.)

This time includes the entire month of March (31 days) and $55-31=24$ days of February. Therefore, the viewing will start $28-24=4$ days from the beginning of February, that is, on February 5, 2023.

In the series, there are $50+5 \cdot 55=325$ episodes.

Grading criteria: 20 points for a complete solution with the correct answer. 10 points for correctly finding the number of days but with an incorrect or correct but unexplained date. 0 points for an answer without justification.