The internal rate of return from an investment in new equipment is expected to be 8.5% p.a. If the returns are expected to be $45811 at the end of the first year, -$2568 at the end of the second year and $68825 at the end of the third year, what is the cost of the equipment? (Give your answer as a positive value to the nearest cent, omitting the dollar sign.)

The correct answer is: 93924.37 <---- how did they work this out?