2. The little squirrel dried mushrooms: $85 \%$ were white mushrooms, and the rest were russulas. Then he ate some of the white mushrooms, and now the russulas made up $30 \%$ of the remaining mushrooms. What part of the mushrooms did the little squirrel eat?
Answer: $\frac{1}{2}$.

Solution: Russulas made up $15\%$ of the mushrooms, then the percentage of russulas doubled, which means the number of mushrooms decreased by half.

Comment: Correct solution - 20 points. A correct solution with an arithmetic error - 15 points. The equation is correctly set up but not brought to the correct solution - 10 points. The solution is started and there is progress - 5 points. The solution is started but the progress is insignificant - 1 point.