How much would you charge as a babysitter!?

Hi ladies!! Help me out. I've been asked to babysit this Sunday from 7pm-12am...the thing is I haven't babysat in so long and I was asked what I would charge. I will also be babysitting two kids, 2 yr old and a 5 yr old. What would you charge for something like this? Or what have you been charged before. thanks so much!!