<p>A real estate investment has the following characteristics:</p><p>Annual rental income=1800000</p><p>Annual operating expenses=1200000</p><p>Available mortgage rate=6%</p><p>Financing percentage=90%</p><p>Required holding period=5years</p><p>Investor Tax rate=25%</p><p>问value of the investment</p><p>答案是（1800000-1200000）/0.15=4000000</p><p>请问0.15是怎么来的呢</p>