A job can be completed in 6 hours and B in 12 hours, A can be completed in 8 hours and B in 6 hours. If A does it for 3 hours and then B continues to do it, how much time will it take to complete it?
一件工作甲做6时、乙做12时可完成，甲做8时、乙做6时也可以完成．如果甲做3时后由乙接着做，那么还需多少时间才能完成？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">12 - 6</gadget>
<output>6</output>

<gadget id="calculator">8 - 6</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">(1/10) * 3</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">18 + 12</gadget>
<output>30</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(7/10) / (1/30)</gadget>
<output>21</output>

<result>21</result>