SOLVE ! white spots

A piece of machinery costs $10,000 and has no salvage value after it is installed. The manufacturer's warranty will pay the first year's maintenance and repair costs. In the second year, maintenance costs will be $1000, and they will increase on a $1100 arithmetic gradient in subsequent years. Also, operating expenses for the machinery will be $400 the first year and will increase on a $600 arithmetic gradient in the following years. If interest is 8%, compute the machinery's economic life that minimizes the EUAC. That is, find its