The road construction team builds a road with a length of 3600 meters. After repairing a section on the first day, if it repairs the full length (1/5) on the second day, then the repaired is exactly the full length (3/4). After repairing for a while on the first day, how many meters are left unrepaired?
修路队修一条长3600米的公路，第一天修了一段以后，如果第二天再修全长的(1/5)，那么已修的恰好是全长的(3/4)．第一天修了一段后，还有多少米没有修？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/4) - (1/5)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">3_600 * (11/20)</gadget>
<output>1_980</output>

<gadget id="calculator">3_600 - 1_980</gadget>
<output>1_620</output>

<result>1_620</result>