For a right-angled trapezoid, if the lower base is increased by 1.5 meters, the area will be increased by 3.15 square meters; if the upper base is increased by 1.2 meters, a square will be obtained. What is the area of this rectangular trapezoid?
一个直角梯形，若下底增加1.5米，面积就增加3.15平方米；若上底增加1.2米，就得到一个正方形．这个直角梯形的面积是多少平方米？
<gadget id="calculator">2 / 1.5</gadget>
<output>1.333333</output>

<gadget id="calculator">3.15 * 1.333333</gadget>
<output>4.199999</output>

<gadget id="calculator">4.199999 - 1.2</gadget>
<output>2.999999</output>

<gadget id="calculator">2.999999 + 4.199999</gadget>
<output>7.199998</output>

<gadget id="calculator">4.199999 / 2</gadget>
<output>2.1</output>

<gadget id="calculator">7.199998 * 2.1</gadget>
<output>15.119996</output>

<result>15.119996</result>