There are 40 students in a class, and the ratio of the number of girls to the total number is 3:8, how many boys are there?
某班有学生40人，女生人数与总人数的比是3：8，则男生有多少人．
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 - (3/8)</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">40 * (5/8)</gadget>
<output>25</output>

<result>25</result>