Qingfeng Township wants to dig a 1,200-meter-long canal. After digging a section on the first day, if 10% of the total length is dug on the second day, then exactly 30% of the total length has been dug. After digging for a while on the first day, how many meters are left undug?
庆丰乡要挖一条长1200米水渠，第一天挖了一段以后，如果第二天再挖全长的10%，那么，已挖的恰好是全长的30%．第一天挖了一段以后，还有多少米没有挖？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(3/10) - (1/10)</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">1_200 * (4/5)</gadget>
<output>960</output>

<result>960</result>