For a trapezoidal vegetable field, its upper base is 21m. The bottom is 45m, and the area is 759m**2. How many meters is it high?
一块梯形菜地，它的上底是21m．下底是45m，面积是759m**2．它的高是多少米？
<gadget id="calculator">21 + 45</gadget>
<output>66</output>

<gadget id="calculator">2 / 66</gadget>
<output>1/33 = around 0.030303</output>

<gadget id="calculator">759 * (1/33)</gadget>
<output>23</output>

<result>23</result>