the mall charges 40 cents for the first hour of parking and $ 3 for each additional hour until the customer reaches 4 hours , after that the parking fee is $ 2 per hour . if mr . park parked his car in the mall for 7 hours and 30 minutes , how much is he going to pay ?
"0.40 + 2 * 2 + 1 * 2 + 0.40 = $ 6.8 answer : $ 6.8"
add(add(multiply(3, 3), multiply(add(subtract(7, 4), divide(40, const_100)), 2)), divide(40, const_100))