Zhang Qiang’s family used 180 kwh of electricity in June, saving 20% compared to May. How much kwh did they use in May?
张强家六月份用电180度，比五月份节约20%，五月份用电多少度．
<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">180 / (4/5)</gadget>
<output>225</output>

<result>225</result>