Divide the number of nails by the number of minutes:
16 1/5 ÷ 15 = 1 2/25 per minute
48 3/5 ÷ 45 = 1 2/25 per min
59 2/5 ÷ 55 = 1 2/25 per min
We have the number of nails produced per minute, to calculate the number of nails in an hour multiply it by 60, because 60 minutes= 1 hour:
1 2/25 x 60 = 64 4/5