Final answer:
The lawnmower would need to be completely filled 42 times during the week. It would cost $840 to mow one average lawn in terms of fuel only.
Step-by-step explanation:
Part A: To find out how many times the lawnmower would have to be completely filled during the week, we need to divide the total amount of gas used by the lawnmower, which is 316 gallons per lawn. Since the lawnmower cuts 42 lawns every week, the total amount of gas used in a week is 316 gallons per lawn * 42 lawns = 13,272 gallons.
To find out how many times the lawnmower would be filled, we divide the total amount of gas used by the capacity of a full tank, which is 316 gallons. So, the number of times the lawnmower would be completely filled during the week is 13,272 gallons ÷ 316 gallons = 42 times.
Part B: To find out the cost of mowing one average lawn, we multiply the cost of a full tank of gas, which is $20, by the number of times the lawnmower is filled during the week, which is 42 times. So, the cost of mowing one average lawn is $20 × 42 = $840.