Answer:
Useful Output = 35 J
Explanation:
The useful energy output of the car must be equal to the difference between the total input energy supplied to the car and the energy wasted by the car:
Useful Output = Total Input - Waste
where,
Total Input = 120 J
Waste = 85 J
Therefore,
Useful Output = 120 J - 85 J
Useful Output = 35 J
