A project is completed in 30 days alone, B in 60 days, and C in 40 days. Three people work together, A has to rest for every 2 days, B has to rest for every 3 days, and C has to rest for every 5 days. Taking one day off, how many days will it take to complete the project?
一项工程，甲单独做30天完工，乙60天完工，丙40天完工，三人合做，甲每做2天要休息一天，乙每做3天要休息一天，丙每做5天要休息一天，那么完成这项工程时共需要多少天？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/3) - (2/15) - (1/15) - (1/8)</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/120) / (1/60)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">12 + 5 + (1/2)</gadget>
<output>35/2 = around 17.5</output>

<result>35/2 = around 17.5</result>