Please help with part b!

Payback period Laredo Laminates is considering the purchase of new production technology equipment requiring an initial $1,500,000 investment and having an expected ten year life. At the end of its life, the equipment would have no salvage value. By installing the new equipment, the firm's annual labor and quality costs would decline by $600,000 a. Compute the payback period for this equipment. years b. Assume instead that the annual cost savings would vary according to the following schedule: Compute the payback period under the revised circumstances. x years