First find how many minutes Jenna tans each of the first two weeks: 30 minutes/day * 2 days/week = <<30*2=60>>60 minutes/week
Then multiply that number by the number of weeks to find how many minutes Jenna tans in the first half of the month: 60 minutes/week * 2 weeks = <<60*2=120>>120 minutes
Then subtract that time from the total time Jenna can spend tanning to find how many more minutes she can tan: 200 minutes - 120 minutes = <<200-120=80>>80 minutes
#### 80