How much do I charge as a babysitter/ teaching eng (Brasilia)

Hi, I am American and I am moving to Brasilia and I was asked to babysit for two young Brazilian children, while speaking english. I have my masters degree in early and childhood education and I have my certified to teach english as a foreign language.

How much would I charge hourly? How much would I charge if I were to specifically tutor these students in English? Any help would be greatly appreciated!!