A job can be completed in 4 days by the cooperation of A, B and C. If A does it for 4 days, then B and C cooperate for 2 days to complete the job (13/18), then A completes the job every day What fraction of?
一项工作，甲、乙丙三人合作4天可以完成，如果甲做4天后，再由乙、丙合作2天，可以完成这项工作的(13/18)，那么甲每天完成这项工作的几分之几？
<gadget id="calculator">13 / 18</gadget>
<output>13/18 = around 0.722222</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(13/18) - (1/2)</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">(2/9) / 2</gadget>
<output>1/9 = around 0.111111</output>

<result>1/9 = around 0.111111</result>