Answer:
(x+4)
Step-by-step explanation:
First find the amount of each payment:

The total cost will be 40 payments plus service charges.

The percentage is the service charge divided by total cost:
Answer:
depth of -117 feet
Step-by-step explanation:
24 hours 72 feet, so one hour 72/24 = 3 feet
after 15 hours, another 3*15 = 45 feet, so the depth become 72 + 45 = 117 feet