The students participate in the chorus. Boys stand in 5 rows, with 12 people in each row. The number of boys is twice that of girls. How many girls are there?
同学们参加大合唱，男生站5行，每行12人，男生的人数是女生的2倍，女生有多少人．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">12 * (5/2)</gadget>
<output>30</output>

<result>30</result>