A, B, and C need 6 hours to complete a project. If A works for 6 hours and B and C cooperate for 2 hours, they can complete the project (2/3); if A and B cooperate for 3 hours, C can complete it in 6 hours. Engineering (2/3). How long will it take for this project to be completed by the cooperation of A and C?
甲、乙、丙完成一项工程需要6小时，如果甲工作6小时，乙、丙合作2小时，可以完成工程的(2/3)；如果甲、乙合作3小时，丙做6小时也完成工程的(2/3)．这项工程由甲和丙合作要多久完成？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) * 3</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(2/3) - (1/2)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">6 - 3</gadget>
<output>3</output>

<gadget id="calculator">(1/6) / 3</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 3</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/18) + (1/9)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<result>6</result>