First we need to calculate the total cost.
The seniors will rent limousine from 8:00 pm till 1:00 am. So total time of rent = 5 hours
Total charges = Charges of first 3 hours + Charges of next 2 hours + Tip
So,
Total charges = $180 + 2($30) +$20 = $260
Thus the total amount the 8 seniors will have to pay is $260. The amount each senior will have to pay is $260/8 = $32.5
Therefore, each student will have to pay $32.5