On a trip, a motorist purchased gasoline as follows: 56 litres at $0.99 per litre; 64 litres

Question:

On a trip, a motorist purchased gasoline as follows: 56 litres at $0.99 per litre; 64 litres at $1.065 per litre; 70 litres at $1.015 per litre; and 54 litres at $1.045 per litre.
(a) What was the average number of litres per purchase?
(b) What was the average cost per litre?
(c) If the motorist averaged 8.75 km per litre, what was the average cost of gasoline per kilometre?