In Pittsburgh it would be appropriate to pay another mom with kids of her own $40 for the day.
If it going to be an all-summer thing, it would almost almost always be cheaper & better for everybody to put the kids in Summer camp.
What is a good rate for 2 kids age 9 and 6 for an eight hour day?
For 40 dollars a day that would only be 200 a week--I don't know of any summer camps around here that are that cheap. My daughter is going to a summer camp at the beach that is from 9:30-2 and it is 260.00 for the week. I used to have her in a camp when she was younger that I could drop her off at 7am and pick her up between 4-6 and it was over 400 a week.
My 16 year old is making $5/hr this summer watching a 6 year old and an 11 year old, for comparison's sake.
I am sorry but that is the rate I made 23+ years ago babysitting and I thought that was a great rate back then. I think your child needs to ask for more money. Even 8 years ago+ I'd pay our babysitter 8-10 an hour for watching 2 boys who would have been 7 and 8 (that was 8 years ago). IF I had 2 sitters (sometimes 2 neighbor boys would watch on weekend nights cause they were good friends and great sitters) I'd pay them BOTH the same amount...the 8-10 an hour.
only problem is in reality... if you have a parent making min wage or even a little over there is no way the can afford to pay that much per hour.