Denny Corporation is considering replacing a technologically obsolete machine with a new state-of-the-art numerically controlled machine. The new machine would cost $310,000 and would have a ten-year useful life. Unfortunately, the new machine would have no salvage value. The new machine would cost $52,000 per year to operate and maintain, but would save $93,000 per year in labor and other costs. The old machine can be sold now for scrap for $31,000. The simple rate of return on the new machine is closest to (Ignore income taxes.):