Final answer:
To find the amount of frosting David will use on each dessert, divide the total amount of frosting by the number of desserts. In this case, David will use 3/20 cup of frosting on each dessert.
Step-by-step explanation:
To find how much frosting David will use on each dessert, he needs to divide the total amount of frosting by the number of desserts. So, 3/5 of a cup divided by 4 desserts would be:
(3/5) / 4 = (3/5) * (1/4)
To multiply fractions, multiply the numerators together and multiply the denominators together. So, (3/5) * (1/4) = 3/20 cup of frosting.
Therefore, David will use 3/20 cup of frosting on each dessert.