Is this a solution for paying a babysitter on Shabbos?
I had a babysitter on Thursday night, Friday night, and Shabbos day.
We never agreed on the amount of money paid per hour. Can I tell her that we’re only paying her for Thursday night and I pay her a lot more than what I decided? And the total is going to be as if I paid her the amount that I decided per hour for Thursday and Friday and Shabbos day?
If she babysits some time for free then you can pay her only for Thursday and for Shabbos would be for free.
However if you always pay her to babysit, and she is only doing it for free because you’re paying her a lot for Thursday then it would not be allowed.
How about if I do her a favor in return? for example, I substitute her class for free in return for her babysitting my child for free on Shabbos?
Still a problem.
Also there can be a question of Ribbis in such a case.
ראה רע”א סימן ש”ז סעיף י, ושש”כ פכ”ח הערה קכו.
וראה שוע”ר אדה”ז הלכות ריבית ועיסקא סעיף ו.