Dongfeng Washing and Dyeing Factory saves 20% of water consumption per day compared to the past. The original 390 tons of water is now used 30 days more than in the past. How many tons of water is used per day now?
东风洗染厂，每天用水量比过去节约20%，原有390吨水，现在比过去多用30天，现在每天用水多少吨？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 30</gadget>
<output>1/150 = around 0.006667</output>

<gadget id="calculator">390 * (1/150)</gadget>
<output>13/5 = around 2.6</output>

<result>13/5 = around 2.6</result>