A factory used 120 tons of coal in March, and saved 20% in April compared with March. What percentage of coal used in April accounted for March?
某工厂三月份用煤120吨，四月份比三月份节约20%，四月份用煤占三月份百分之几？
<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>

<result>4/5 = around 0.8</result>