To produce a batch of parts, A alone will complete it in 30 days, and B alone will complete it in 40 days. Now B will do it in 5 days first, and then A and B will cooperate. How many days will it take to complete the task?
生产一批零件，甲独做30天完成，乙独做40天完成，现在乙先做5天，后由甲乙合作，还需要几天完成任务？
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">(1/40) * 5</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 - (1/8)</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) + (1/40)</gadget>
<output>7/120 = around 0.058333</output>

<gadget id="calculator">(7/8) / (7/120)</gadget>
<output>15</output>

<result>15</result>