A piece of laborsaving equipment has just come onto the market that Mitsui Company could use to reduce costs in one of its plans. Relevant data relating to the equipment follow:

$-$ Purchase cost of the equipment: $$432,000$

$-$ Annual cost saving that will be provided by the equipment: $$90,000$

$-$ Life of the equipment: $12$ years

Required:

$1.$ Compute the payback period for the equipment. If the company requires a payback period of four years or less, would the equipment be purchased?

$2.$ Compute the IRR on the equipment?

Please show me how to solve requirement $2$ in detail