A certain unit used 180 tons of water last month, an increase of -20% this month, how many tons of water is used this month?
某单位上月用水180吨，本月增长-20%，本月用水多少吨？
<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>144</output>

<result>144</result>