Summer Babysitting Rates?

I will likely be babysitting for three different families on set days this summer, and I would like some input as to what I should accept to be compensated. I do not drive, and I live in the suburbs of a moderately sized city.

Family 1

2 days a week, 4 hours each

5 year old girl

Family 2

1 day a week, 4 hours

3 year old boy, 6 year old boy

Family 3

1 day a week, 4-8ish hours, we haven't discussed yet

6 year old boy, 8 year old boy

Thanks!