When Xiaohong is 3 years old, her mother's age is the same as Xiaohong's age this year; when her mother is 78 years old, Xiaohong's age is the same as her mother's age this year. How old is mother this year?
当小红3岁时，妈妈的年龄和小红今年的年龄相同；当妈妈78岁时，小红的年龄和妈妈今年的年龄相同．妈妈今年多少岁．
<gadget id="calculator">3 + 27</gadget>
<output>30</output>

<result>30</result>