The answer is 20 prints.
Explanation:
The total cost is $11. Joseph paid $8 for the SUBSCRIPTION (NOT PRINTS) already, so we take away the 8 from 11, equaling in $3 left.
The question is asking for the amount of prints. Now that we only have 3 dollars left, we just divide that by the cost of each print (0.15) to see how many prints can go into that cost.
3 divided by 0.15 is 20. So, Joseph purchased 20 prints.