(1/5) of a project, A and B can complete the whole project by cooperating in 4 days. If two people cooperate for 8 days first, the rest can be completed by A alone in 18 days. How many days will it take for B to complete the project alone?
一项工程，甲、乙两人合作4天可以完成全部工程的(1/5)．如果先由两人合作8天，余下的由甲单独做18天可以完成．这项工程由乙单独做要多少天完成．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 4</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 8</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) / 18</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/20) - (1/30)</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">1 / (1/60)</gadget>
<output>60</output>

<result>60</result>