The school bought a batch of balls and distributed them to grades 1, 2 and 3 according to the ratio of 7:3:2. As a result, grade 2 got 36 fewer balls than grade 1. How many balls did the school buy in total?
学校买一批皮球，按7：3：2分给了一二三年级班，结果二年级比一年级少分36只，学校共买来皮球多少只？
<gadget id="calculator">7 + 3 + 2</gadget>
<output>12</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

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

<gadget id="calculator">(7/12) - (1/4)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">36 / (1/3)</gadget>
<output>108</output>

<result>108</result>