Answer: The store sold 13 31/40 boxes of nails .
Explanation:
Hi, to answer this question we have to simply add the fraction of the boxes of nails that were sold. (Both large and small nails boxes)
Mathematically speaking:
6 3/8 + 7 2/5 = 6 15/40 + 7 16/40 = 13 31/40
The store sold 13 31/40 boxes of nails .
Feel free to ask for more if needed or if you did not understand something.