Miranda and her family share a family data plan for their cell phones this month her mom used 400 her father used 350 and her little sister use three 200 minutes they want the average number of minutes to be 350 minutes how many minutes should miranda use

Assuming you meant her sister used 200 minutes which im still a little unclear of

if everyone in the family used 350 minutes it would add up to 1400, this is the number you want your minutes to add up to
400
350
200 thats 950
subtract 950 from 1400 and you have 450

450 Minutes is your answer

The answer to your question is b