This is inspired by a lot of threads in which people talk about the cost of a babysitter.
It's 1998/1999, you have a 13 year old son and you want to go 300 yards down the road with your husband every Sunday evening for a 2.5/3 hour drink at the wine bar.
You will put him to bed before the sitter comes, usually, though he might still be hanging around. He won't need to be tucked in though, he will put himself to bed on those occasions, he is 13 after all, he's an only child.
The sitter is a 15.5 year old girl. Her 18 year old sister used to do the job but has gone on to uni so suggested the younger girl take over.
It's an easy job. She'll be dropped off by her parents, then sit on the sofa from 7-10, watch TV or do her homework on her lap. At 10 she'll be dropped home, half a mile away. By your dh. You'll leave her a crunchie or a double decker, and she can help herself to water.
You leave her wages on the table every week without fail.
But...
How much is in the envelope?
Hint: according to the BOE inflation calculator, money then would be about twice as much in today's prices - bit less, so add if you're paying her in 1998/9 money, or today's money, iyswim.