In a mathematics class, it takes (1/12) hours to review, (1/3) hours to teach new lessons, and (1/4) hours to practice. How many hours does this class have?
一堂数学课，复习用去(1/12)小时，讲新课用去(1/3)小时，学生练习用去(1/4)小时，这节课共有几小时？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/12) + (1/3) + (1/4)</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>