4. In grandmother's garden, apples have ripened: Antonovka, Grushovka, and White Naliv. If there were three times as many Antonovka apples, the total number of apples would increase by $70 \%$. If there were three times as many Grushovka apples, it would increase by $50 \%$. By what percentage would the total number of apples change if there were three times as many White Naliv apples?
Solution. First method. If the quantity of each type of apple were three times as much, the total number of apples would increase by $200 \%$. Of this increase, $70 \%$ is due to Antonovka, and $50 \%$ is due to Grushovka. Therefore, the increase due to White Naliv would be $200 \%-70 \%-50 \%=80 \%$.

Second method. Since adding twice the amount of Antonovka results in a $70 \%$ increase, Antonovka makes up 0.35 of all apples. Similarly, Grushovka makes up 0.25 of all apples. Therefore, the share of White Naliv is 0.4. If you add 0.4 twice to a number, the number will increase by $80 \%$. Answer: $\mathbf{8 0 \%}$.

Comment: The reasoning is correct, but a computational error has been made - 5 points. Only the correct answer is provided or it is obtained by considering a specific example - 1 point.