Given:
Total number of books is, N = 20.
Number of books donated is, d = 2/5 of books.
The objective is to find the number of books donated.
Consider the number of books donated as x.
[tex]\begin{gathered} x=\frac{2}{5}\cdot20 \\ x=8 \end{gathered}[/tex]Hence, the number of books donated is 8.