If A alone takes 8 hours to complete a project and B alone takes 12 hours to complete it, if A does it in 4 hours and B does it in 3 hours, how much of the project can be completed?
一项工程，甲独做需要8小时完成，乙独做需要12小时完成，如果甲做4小时、乙做3小时，能完成这项工程的多少．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) * 4</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(1/12) * 3</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) + (1/4)</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>