Pronghorn's Lawn service needs to purchase a new lawnmawer $8,306 to replace an old lawnmower that cannot be repaired. The new lawnower is expected to have a useful life of 4 years, with no salvage value at the end of that period.

a.) If the Pronghorn's required rate of return is 12% what level of annual cash savings, just the lawnmower generate to be considered an acceptable investment under the net present value method?

b.) If pronghorn's required rate of return is 20%, what level of annual cash savings must the lawnmower generate to be considered an acceptable investment under the net present value method?