chemical fertilizer factory produced 180 tons of fertilizer in October, which was 20 tons more than the original plan. By what percentage?
某化肥厂十月份生产化肥180吨，比原计划超产20吨，超产了百分之几？
<gadget id="calculator">180 - 20</gadget>
<output>160</output>

<gadget id="calculator">20 / 160</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>