There are 4 members in Xiao Ming's family. The combined age of the whole family is 79 years old. His mother is 1 year older than his father, and his sister is 2 years younger than Xiao Ming. 4 years ago, the sum of the ages of their whole family was 64 years old, you know how old his mother is.
小明一家4口人，全家人今年的年龄之和是79岁，母亲比父亲大1岁，妹妹比小明小2岁．4年前，他们全家人的年龄之和是64岁，你知道他妈妈今年多少岁．
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">79 - 5 - 3</gadget>
<output>71</output>

<gadget id="calculator">1 + 71</gadget>
<output>72</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">72 / 2</gadget>
<output>36</output>

<result>36</result>