If the area of a parallelogram remains the same, how much should the base be shortened when the height increases by 40%.
平行四边形面积不变，当高增加40%时，底应该缩短多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>