The area of a trapezoidal field is 75m**2, the bottom is 10m, and the top is 5m. Find its height.
一块梯形田地的面积为75m**2，下底是10m，上底是5m，求它的高．
<gadget id="calculator">10 + 5</gadget>
<output>15</output>

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

<gadget id="calculator">75 * (2/15)</gadget>
<output>10</output>

<result>10</result>