Answer:
$108.
Explanation:
We have been given that Anna and Joe's father donated $3 for every lap they swam in a swim-a-thon Ann swam 21 laps and Joe swam 15 laps. We are asked to find the amount of money their father donated using distributive property.
![\text{Amount of money their father donated}=\$3(21+15)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/wym10dqxw42nzm6jit2r0atpo1funlbeg8.png)
![\text{Amount of money their father donated}=\$3*21+\$3*15](https://img.qammunity.org/2019/formulas/mathematics/middle-school/1abuoeswuav53wrb80v83evqg10f8e7mwa.png)
![\text{Amount of money their father donated}=\$63+\$45](https://img.qammunity.org/2019/formulas/mathematics/middle-school/gpqlyu25ihwhjz2ftwatqsqhqvkb1hoo4d.png)
![\text{Amount of money their father donated}=\$108](https://img.qammunity.org/2019/formulas/mathematics/middle-school/q9rdp2fpc84cpa3scumisaxnxxywmbbr5w.png)
Therefore, the amount of money donated by their father was $108.