There are only two classes of sixth grade in a certain school, with a total of 75 students, (5/7) of the first class are boys, and (7/13) of the second class are girls, so how many girls are there in the sixth grade of this school?
某校六年级只有两个班，共有75人，一班人数的(5/7)是男生，二班人数的(7/13)是女生，则这个学校六年级共有女生多少人．
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">49 * (5/7)</gadget>
<output>35</output>

<gadget id="calculator">49 - 35</gadget>
<output>14</output>

<gadget id="calculator">14 + 14</gadget>
<output>28</output>

<result>28</result>