Given, total number of apples picked, T=64.
The percentage of green apples, R=40%.
Let N be the number of green apples picked.
So,
[tex]\begin{gathered} R=\frac{N}{T}\times100 \\ N=\frac{R}{100}\times T \\ N=\frac{40}{100}\times64 \\ N=25.6 \end{gathered}[/tex]Therefore, 25 green apples were picked.