Now it is planned to assign the task of excavating a tunnel to two engineering teams, A and B. The two teams start work from both ends at the same time. When the two teams open the tunnel, the ratio of the workload completed by the two teams is 5:4. At the same time, because team A updated the equipment, its efficiency increased by 20%. When the two teams opened the tunnel, team B excavated 80 meters less than planned. What is the total length of the tunnel?
现在计划把开凿一条隧道的任务分配给甲、乙两个工程队，两队同时从两端开工，两队开通这条隧道时，甲、乙两队完成工作量的比是5：4，实际同时开工时，由于甲队更新了设备，使其效率提高了20%，这样两队开通隧道时，乙队比计划少开凿了80米，这条隧道全长多少米．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(6/5) / 4</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">5 * (3/10) * 80</gadget>
<output>120</output>

<gadget id="calculator">80 + 120</gadget>
<output>200</output>

<gadget id="calculator">5 * (3/10) * 4</gadget>
<output>6</output>

<gadget id="calculator">6 - 5</gadget>
<output>1</output>

<gadget id="calculator">200 / 1</gadget>
<output>200</output>

<gadget id="calculator">5 * 200</gadget>
<output>1_000</output>

<gadget id="calculator">4 * 200</gadget>
<output>800</output>

<gadget id="calculator">1_000 + 800</gadget>
<output>1_800</output>

<result>1_800</result>