Seven years ago, the age of the mother was 6 times that of the son. The son is 12 years old this year. How old is the mother?
7年前，妈妈年龄是儿子的6倍，儿子今年12岁，妈妈今年多少岁．
<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">30 + 7</gadget>
<output>37</output>

<result>37</result>