For a project, team A alone will complete the project in 4 days (1/7), and team B alone will take 40 days to complete it. If team A works alone for 11 days and then team B joins in, the two teams will work together to complete the rest of the project , how many days will it take to complete?
一项工程，甲队单独做4天完成这项工程的(1/7)，乙队单独做需要40天完成，如果甲队先独做11天后乙队加入，两队合做剩下的工程，还需要多少天完成？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/7) / 4</gadget>
<output>1/28 = around 0.035714</output>

<gadget id="calculator">(1/28) * 11</gadget>
<output>11/28 = around 0.392857</output>

<gadget id="calculator">1 - (11/28)</gadget>
<output>17/28 = around 0.607143</output>

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">(1/28) + (1/40)</gadget>
<output>17/280 = around 0.060714</output>

<gadget id="calculator">(17/28) / (17/280)</gadget>
<output>10</output>

<result>10</result>