If A and B work together to complete a project in 6 days, and A works alone in 9 days, the work efficiency of A working alone is much slower than that of working together.
一项工程，甲乙合做6天完成，甲单独做9天完成，甲单独做的工效比二人合做的工效慢多少．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

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

<gadget id="calculator">(1/6) - (1/9)</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(1/18) / (1/6)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>