A project can be completed in 8 days by A alone, 14 days by B alone, and 4 days jointly by A and B, how much of the whole project can be completed.
一件工程，甲单独做8天可以完成，乙单独做14天可以完成，甲乙合做4天，可以完成全工程的多少．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 14</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">(1/8) + (1/14)</gadget>
<output>11/56 = around 0.196429</output>

<gadget id="calculator">(11/56) * 4</gadget>
<output>11/14 = around 0.785714</output>

<result>11/14 = around 0.785714</result>