A trapezoid, the ratio of the upper and lower bases is 2:5, the upper base is 18 cm shorter than the lower base, and the height is 5 cm, what is the area of the trapezoid in square centimeters?
一个梯形，上下底的比是2：5，上底比下底短18厘米，高是5厘米，这个梯形的面积是多少平方厘米．
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">18 / 3</gadget>
<output>6</output>

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

<gadget id="calculator">18 + 12</gadget>
<output>30</output>

<gadget id="calculator">12 + 30</gadget>
<output>42</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">42 * (5/2)</gadget>
<output>105</output>

<result>105</result>