The ratio of the number of people in classes A and B is 3:4, and there are 42 people in class A. Do you know how many people are in classes A and B?
甲、乙两班人数的比为3：4，其中甲班有42人，你知道甲、乙两班共有多少人吗？
<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">42 / (3/7)</gadget>
<output>98</output>

<result>98</result>