I know the minimum wage for under-18s is £3.70/hour.
What do you think a 15-year-old babysitter should be paid, and what part of the country are you in please?
Dd aged 15 has a lot of expensive 'wants' and needs to start paying her own way if she's going to get them.
(She's brilliant and very patient with small children btw, and trained in first aid)