cannot figure out the denominator, its not the investment of 336,000

Required information [The following information applies to the questions displayed below.] Project Y requires a $336,000 investment for new machinery with a four-year life and no salvage value. The project ylelds the following annual results, Cash flows occur evenly within each year. (PV of \$1, EV of \$1, PVA of \$1, and EVA of \$1) Note: Use appropriate factor(s) from the tables provided. 3. Compute Project Y 's accounting rate of return