There are not enough teaching materials in the cultural elementary class. For the time being, every two people use one Chinese book, every three people use one math book, and every four people use one English book. The whole class shares 91 textbooks. How many people are there in the class?
文化初级班的教材不够，暂时每两人用一本语文书，每3人用一本数学书，每4人用一本英语书，全班共用了91本教材，问全班有多少人？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</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">(1/2) + (1/3) + (1/4)</gadget>
<output>13/12 = around 1.083333</output>

<gadget id="calculator">91 / (13/12)</gadget>
<output>84</output>

<result>84</result>