The area of a trapezoid is 49 square centimeters, the height is 7 centimeters, the upper base is 4 cm, and the lower base is how many centimeters.
一个梯形的面积是49平方厘米，高是7厘米，上底是4厘米，下底是多少厘米．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">49 * (2/7)</gadget>
<output>14</output>

<gadget id="calculator">14 - 4</gadget>
<output>10</output>

<result>10</result>