The ratio of A and B is 3:7, A's number is 15, what is B's number?
甲、乙两数的比是3：7，甲数是15，乙数是多少．
<gadget id="calculator">7 / 3</gadget>
<output>7/3 = around 2.333333</output>

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

<result>35</result>