Answer:
11, 12.
Step-by-step explanation:
Let q represent number of quarters.
We have been given that Caroline has a maximum of 15 coins worth at least $2.85 combined. We are also told that Caroline has 3 dimes. This means that total coins are less than or equal to 15.
We can represent this information in an inequality as:

We are also told that the coins worth at least $2.85 combined. This means that the worth of all coins is greater than or equal to 2.85.
We know that each dime is worth $0.10 and each quarter is worth $0.25.

Now, let us solve our system of inequalities.
From 1st inequality, we will get:


From 2nd inequality, we will get:





Upon combining our both inequalities, we will get:

This means that numbers of quarters would be greater than or equal to 10.2 and less than or equal to 12.
Since we cannot have 0.2 of a coin, therefore, Caroline could have 11 or 12 quarters.