There are 15 boys in class 6 and 2. The ratio of boys to girls is 3:4. How many people are there in the class?
六2班有男生15人，男生和女生人数的比是3：4，全班有多少人？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">15 / (3/7)</gadget>
<output>35</output>

<result>35</result>