Im babysitting , how much should I get paid? **Details Inside?

Im babysitting a 2 year old and a 4-5 year old. Im going to be there for 7-8 hours. I have to cook, change diapers, and play with them. Also the father of the children will be right next door at thier neibors house doing constuction all day. I am babysitting for 4 days in a row, all of them 7-8 hours.