To determine how much money you still owe, we need to know the total cost of the gas you pumped. Since that information is not provided in your question, I cannot calculate the amount owed directly. If you provide the total cost of gas, I can help you find out how much you still owe after your friend gave you $31.56.
However, based on your options and assuming you meant to convey that the total cost of gas was a certain amount, if we were to match your friend's contribution of $31.56 with the options provided:
- If the total was less than $31.56: Right response would be "Nothing, this covered the total cost of gas."
- If the total was $40.01: You would owe $8.45.
- If the total was $40.56: You would owe $9.45.
- If the total was $103.13: You would owe $71.57.
Please provide the total cost of gas to clarify.