please be careful with numbers and percent

Old Southwest Canning Co. has determined that any one of four machines can be used in its chili-canning operation. The cost and revenues of the machines are estimated below, and all machines have a 7-year life. If the minimum attractive rate of return is 10% per year, determine the incremental rate of return of the last comparison on the basis of a rate of return analysis. (As of %) Machine First Cost, $ -85,000 -147,000 -316,000 -318,000 Annual Revenue, $ 17,000 49,000 79,000 53,000 3 Answer: 9.92