In a trapezoidal piece of paper with an upper base of 15 cm, a lower base of 25 cm, and a height of 12 cm, cut out the largest triangle. What is the remaining area in square centimeters?
在一个上底是15厘米，下底是25厘米，高是12厘米的梯形纸片中，剪下一个最大的三角形，剩下的面积是多少平方厘米．
<gadget id="calculator">15 + 25</gadget>
<output>40</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">40 * 6</gadget>
<output>240</output>

<gadget id="calculator">25 * 6</gadget>
<output>150</output>

<gadget id="calculator">240 - 150</gadget>
<output>90</output>

<result>90</result>