I need help with this question please?! I'm having a hard time answering it!

Answer:
£0.40
Step-by-step explanation:
Divide £40 by £3.30 to find the number she can buy
£40 ÷ £3.30 = 12.1212..
That is she can buy 12 light bulbs
cost = 12 × £3.30 = £39.60
change = £40 - £39.60 = £0.40