Answer:
$21.39
Explanation:
The way we notate money is by putting dollars first, and then cents at the end of the decimal.
For the first amount of money, we have 15 dollars in cash. We have 3 quarters, and each quarter is 25 cents. If we add 25 cents 3 times, we get 75 cents. We are then given 2 nickels, which are 5 cents. We add 10 to 75, and we get 85 cents.

We are then give a singular 5 dollar bill. We also have two quarters, which are again 50 cents. Add 4 to this, and we get 54.

Now we add the two together!
