The average score of students participating in a math competition in a certain school is 75 points. The ratio of the number of boys to girls participating in the competition is 9:5, and the average score of girls is 20% higher than the average score of boys. What is the average score of boys? ．
某校学生参加数学竞赛的平均分是75分，其中参赛的男生人数与女生人数的比是9：5，而女生的平均分比男生平均分高20%，那么，男生的平均分是多少分．
<gadget id="calculator">75 * 9</gadget>
<output>675</output>

<gadget id="calculator">75 * 5</gadget>
<output>375</output>

<gadget id="calculator">675 + 375</gadget>
<output>1_050</output>

<gadget id="calculator">6 / 5</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">5 * (6/5)</gadget>
<output>6</output>

<gadget id="calculator">9 + 6</gadget>
<output>15</output>

<gadget id="calculator">1_050 / 15</gadget>
<output>70</output>

<result>70</result>