Final answer:
The total amount of gas it took to mow the lawn this past summer is 9 gallons (C).
Step-by-step explanation:
To determine the total amount of gas it took to mow the lawn this past summer, Erin multiplied the number of times she mowed the lawn, 24, by the amount of gas it takes to mow the lawn each time, three-eighths of a gallon.
We can calculate this by multiplying 24 by three-eighths:
24 * (3/8) = 72/8 = 9 gallons.
Therefore, the total amount of gas it took to mow the lawn is 9 gallons (C).