A cooling cost 1540 dollars. After four years he sold at half their value. If this is repeated every four years, the payment in the refrigerator the fifth person to buy it and after a few years this purchase was made.
value = 1540 *(1/2)^(n/4)
when n = 0, years, cost = 1540 for person 1
when n = 4 years, cost = 1540/2 for person 2
when n = 8, years, cost = 1540/4 for person 3
etc