Final answer:
To find out how many pints are left for the last box, subtract the total pints already filled from the total pints picked by Harry.
Step-by-step explanation:
To find out how many pints are left for the last box, we need to subtract the total number of pints already filled in the previous boxes from the total number of pints picked by Harry.
Harry filled one box with 9 pints of blueberries. If he filled 10 boxes in total, then the total number of pints filled in the previous boxes would be 9 x 10 = 90 pints.
Harry picked 97 pints of blueberries, so the number of pints left for the last box would be 97 - 90 = 7 pints.