The age ratio of elder brother and younger brother this year is 5:3, elder brother is 15 years old this year, how old is younger brother this year.
哥哥与弟弟今年的年龄比是5：3，哥哥今年15岁，弟弟今年多少岁．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">15 * (3/5)</gadget>
<output>9</output>

<result>9</result>