project can be completed by the cooperation of A, B, and C in 4 hours. If A works for 4 hours and B and C cooperate for 2 hours, the project can be completed (13/18). What is the fraction of the project that A completes per hour How much?
一项工程，甲、乙、丙三人合作4小时可以完成，如果甲工作4小时，乙、丙合作2小时，可以完成这项工程的(13/18)，甲每小时完成工程的几分之几？
<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>