Answer:
He will need 38 more blueberries
Explanation:
If each cupcake will have 6 blueberries and he wants to make 17 cupcakes he will need a total of 102 blueberries (found by multiplying 17 and 6 together). If he already has 64 he will just need to buy 38 more (found by subtracting 64 from 102). I hope this helped, if not then I apologize.