Answer:
At least 15 hours
Explanation:
First, subtract the $75 that her parents will contribute:
250 - 75
= 175
So, from babysitting, she will have to raise $175
Divide this by 12 to find how many hours she has to babysit:
175/12
= 14.583
We have to round this up to a whole number, which will be 15.
So, Missy will have to babysit for a minimum of 15 hours