When quantity demanded is greater than quantity supplied, the resulting shortage causes the price to fall?

You are considering the purchase of one of two machines used in your manufacturing plant. machine 1 has a life of two years, costs $20,000 initially, and then $4,000 per year in maintenance costs. machine 2 costs $25,000 initially, has a life of three years, and requires $3,500 in annual maintenance costs. either machine must be replaced at the end of its life with an equivalent machine. using eac which is the better machine for the firm