Two identical trapezoids are put together to form a parallelogram with a base of 15 cm and a height of 6 cm. What is the area of the trapezoid in square centimeters?
两个完全相同的梯形拼成一个底15厘米，高6厘米的平行四边形，这个梯形的面积是多少平方厘米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<result>45</result>