The original waste rate of a workshop is (1/40), but now it has decreased by 20%, what is the ready-made rate.
某车间原废品率是(1/40)，现下降20%，现成品率是多少．
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 * (1/40) * (4/5)</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">1 - (1/50)</gadget>
<output>49/50 = around 0.98</output>

<result>49/50 = around 0.98</result>