Charging the car

This task is about working out costs for charging an electric car.

illustration: car charging station showing 91.9 cents per KWh

The battery of Mrs Henare's electric car holds 40 KWh (kilowatt-hours) of energy.

One KWh costs 91.9 cents.

 

a) If Mrs Henare's battery already had 15 KWh of energy, how much would it cost to fully charge it?
 
$ __________
 
b) Mrs Henare noticed that she had used three-quarters of her charge. How much will it cost her to fully charge the battery?
 
$ __________
 
c) If Mrs Henare then used $18.38 worth of energy from the full battery, how many KWh would she have left?
 
__________ KWh