A project can be completed by team A alone in 12 hours, and by team B in 15 hours. If the two teams work together, half of the road will be left after how many hours.
一项工程，甲队单独做要12小时完成，乙队单独做要15小时完成，如果两队合做，多少小时后还剩下这条路的一半．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/12) + (1/15)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(1/2) / (3/20)</gadget>
<output>10/3 = around 3.333333</output>

<result>10/3 = around 3.333333</result>