A basket of apples, the first sale of the total number of apples in this basket is 1/4 and 6 (if there are 36 apples, a quarter of it is 9, and a third of it is 12) , sold the remaining one-third and 4 apples for the second time, sold one-half and 3 apples for the third time, and finally left 4 apples. How many apples were there in this basket?
一筐苹果，第一次卖出这筐苹果总个数的四分之一又6个(假如苹果有36个，它的四分之一是9个，它的三分之一就是12个)，第二次又卖出余下的三分之一又4个，第三次卖出余下的二分之一又3个，最后剩下4个，这筐苹果原来有多少个？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 / (1/2)</gadget>
<output>6</output>

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

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

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

<gadget id="calculator">10 / (2/3)</gadget>
<output>15</output>

<gadget id="calculator">15 + 6</gadget>
<output>21</output>

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

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

<gadget id="calculator">21 / (3/4)</gadget>
<output>28</output>

<result>28</result>