How much should I pay a 13 year old to babysit?

I hired a 13 year old to baby sit for me last night, she stayed over night with us after I got home, and I’m taking her back home today. I picked her up 30 minutes away and am returning her 30 minutes away (her little 8 year old sister stayed with us too) what would appropriate pay be for this age? She watched my son alone for about 4 hours I also bought the girls door dash for dinner