We need to calculate the value that represents 65% of 20 marbles. To do that, we have to multiply the fraction that is equivalent to 65% and 20. This is done below:
[tex]\begin{gathered} \text{black}=65\text{ \%}\cdot20 \\ \text{black}=\frac{65}{100}\cdot20 \\ \text{black}=13 \end{gathered}[/tex]13 marbles are black.
