Three people go to a restaurant. Their bill comes to $78.00. They decide to split the cost. One person pays $4.50; the next person pays 3 times that amount. How much will the third person have to pay?

First, figure out how much the second person paid: 4.50×3=13.5
Then, calculate the total amount contributed by the first two people:
$4.50 + $13.50 = $18.00
Finally, calculate how much the third person will have to contribute by subtracting the amount paid ($18.00) from the original amount owed ($78.00):
$78.00 - $18.00 = $60.00