You are the manager of a a large crude oil refinery. As part of the refining process, a certain heat exchanger (operated at high temperatures and with abrasive material flowing through it) must be replaced every year. The annual replacement and downtime cost each year is $101,000. You will save this amount each year if you replace the heat exchanger with one of higher quality that will last at least 10 years at an initial cost of $831,000. The companys MARR is 15% per year. What is the simple payback? Round up to the nearest integer.