The engineering team dug a tunnel. The full length (2/3) of the first month was 104 meters short, and the second month (7/8) of the first month was completed. At this time, there were still 15 meters left to be completed. How many meters is this tunnel?
工程队挖一条隧道，第一个月完成全长的(2/3)少104米，第二个月完成的是第一个月的(7/8)，这时还剩15米没有完成，这条隧道长多少米？
<gadget id="calculator">7 / 8</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">104 * (7/8)</gadget>
<output>91</output>

<gadget id="calculator">91 - 15</gadget>
<output>76</output>

<gadget id="calculator">104 + 76</gadget>
<output>180</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * (7/8)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">(2/3) - 1</gadget>
<output>-1/3 = around -0.333333</output>

<gadget id="calculator">(7/12) + (-1/3)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">180 / (1/4)</gadget>
<output>720</output>

<result>720</result>