Xiaohong is 12 years old this year, exactly her mother's age (2/7), how old is Xiaohong's mother.
小红今年12岁，正好是她妈妈年龄的(2/7)，小红的妈妈比小红大多少岁．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">12 / (2/7)</gadget>
<output>42</output>

<gadget id="calculator">42 - 12</gadget>
<output>30</output>

<result>30</result>