Final answer:
The greatest number of gallons of gas Leonardo purchased last month was 14.32 gallons.
Step-by-step explanation:
The greatest number of gallons of gas Leonardo purchased last month was 14.32 gallons.
To find the greatest number of gallons, we need to compare the numbers given: 14.071, 14.32, 14.199, 14.28, and 14.1 gallons. 14.32 gallons is the largest number among these options, so that is the correct answer.