Jessica will drive 20 minutes, twice every school day (to and from school), so 20 minutes x 2 trips = <<20*2=40>>40 minutes each day.
There are 60 minutes in 1 hour, so 50 hours of driving x 60 minutes/hour = <<50*60=3000>>3,000 minutes.
If you take the 3,000 minutes she needs to drive / 40 minutes driving each day = <<3000/40=75>>75 school days to drive 50 hours.
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