To dig a canal, teams A and B can complete the work in 18 days. Now, Team A will dig alone for 10 days and then leave, and Team B will continue to dig for 30 days to complete the task. Find the work efficiency of Team B.
挖一条水渠，甲、乙两队合挖18天可以完成．现在先由甲队单独挖10天后离去，乙队接着挖30天恰好完成任务．求乙队的工作效率．
<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(1/18) * 10</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">1 - (5/9)</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(4/9) / 20</gadget>
<output>1/45 = around 0.022222</output>

<result>1/45 = around 0.022222</result>