Final answer:
The cost per gallon of gas is $4.38. To find the cost of 18 gallons, multiply the cost per gallon by 18, resulting in a total of $78.84.
Step-by-step explanation:
The question asks to calculate the cost of 18 gallons of gas based on the cost of 6 gallons. To find the cost per gallon, we divide the total cost by the number of gallons. So, for 6 gallons costing $26.28, we calculate:
Cost per gallon = $26.28 / 6 gallons = $4.38 per gallon.
Now, to find out how much 18 gallons would cost:
Cost for 18 gallons = 18 gallons × $4.38 per gallon = $78.84.
Therefore, buying 18 gallons of gas would cost $78.84.