A trapezoid, its upper base is 5 cm, and its lower base is 15 cm. Draw the largest triangle in this trapezoid. The area is 60 square centimeters. What is the area of the original trapezoid in square centimeters?
一个梯形，它的上底是5厘米，下底是15厘米，在这个梯形里画一个最大的三角形，面积是60平方厘米，原来梯形的面积是多少平方厘米．
<gadget id="calculator">5 + 15</gadget>
<output>20</output>

<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">60 * (2/15)</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<result>80</result>