The cubic feet of air the scuba diver used per minute is 1.2 cubic feet of air per minute
Cubic feet of air used per minute = Difference in quantity of air in his tank / difference in time
= (30 - 12) / (3:30pm - 3:15pm)
= 18 / 15
= 1.2 cubic feet of air per minute
Therefore, the cubic feet of air the scuba diver used per minute is 1.2 cubic feet of air per minute
Learn more about unit rate:
https://brainly.com/question/4895463
#SPJ1