project can be completed by A and B working together in 12 days. It is known that the work efficiency of A is (2/3) of that of B, how many days can B alone do it?
一项工程，甲、乙合做12天可以完成．已知甲的工效是乙的(2/3)，则乙单独做多少天可以完成？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 + (2/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">(1/12) / (5/3)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / (1/20)</gadget>
<output>20</output>

<result>20</result>