The average score of the first group in Class 51 is 82.5 in a math test. It is known that there are 5 girls, the average score is 91.5, and the average score of boys is 75. How many boys are there in the first group?
五1班第一大组在一次数学考试中的平均分是82.5，已知女生有5人，平均分是91.5分，男生平均每人考75分，求第一大组中有男生多少人？
<gadget id="calculator">91.5 * 5</gadget>
<output>457.5</output>

<gadget id="calculator">82.5 * 5</gadget>
<output>412.5</output>

<gadget id="calculator">457.5 - 412.5</gadget>
<output>45</output>

<gadget id="calculator">82.5 - 75</gadget>
<output>7.5</output>

<gadget id="calculator">45 / 7.5</gadget>
<output>6</output>

<result>6</result>