To solve this problem you must apply the proccedure shown below:
1. You have that the 10 boxes of nails that were included in the two deliveries,had a total cost of $110.
2. Therefore, you can calculate the cost in dollars of one box of nails (n), as following:
"n" is the cost of one box of nails.
10n=110
n=110/10
n=11 dollars