You are operating an elderly machine that is expected to produce a net cash inflow of $$4,000$ in the coming year and $$4,000$ next year. After that it will give up the ghost. You can replace it now with a new machine, which costs $$15,000$ but is much more efficient and will provide a cash inflow of $$8,000$ a year for $3$ years. You want to know whether you should replace your equipment now or wait two years. Assume that the required rate of return is $6\%.$