A project needs 10 hours to be done by A alone, and 12 hours to be done by B alone. Now A will do 2 hours first. How many hours will A and B need to do the rest?
一项工程，甲独做要10小时，乙独做要12小时，现由甲先做2小时，剩下的由甲、乙合做还要几小时？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 2</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">(1/10) + (1/12)</gadget>
<output>11/60 = around 0.183333</output>

<gadget id="calculator">(4/5) / (11/60)</gadget>
<output>48/11 = around 4.363636</output>

<result>48/11 = around 4.363636</result>