The little girl is 4 years old this year, and the combined age of her and her father will be 50 years later in 8 years, how old is her father this year?
小妹今年4岁，8年后她和爸爸年龄的总和是50岁，爸爸今年多少岁？
<gadget id="calculator">8 + 4</gadget>
<output>12</output>

<gadget id="calculator">50 - 12 - 8</gadget>
<output>30</output>

<result>30</result>