42% of a batch of chemical fertilizers are used up, how much is left?
一批化肥用去42%，还剩多少．
<gadget id="calculator">42 / 100</gadget>
<output>21/50 = around 0.42</output>

<gadget id="calculator">1 - (21/50)</gadget>
<output>29/50 = around 0.58</output>

<result>29/50 = around 0.58</result>