Three years ago, the age of the father was exactly 6 times the age of the son. This year, the combined age of the father and son is 55. How old is the son this year?
三年前爸爸的年龄正好是儿子年龄的6倍，今年父子俩年龄和为55岁，求今年儿子多少岁？
<gadget id="calculator">55 - 3 - 3</gadget>
<output>49</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<gadget id="calculator">49 / 7</gadget>
<output>7</output>

<gadget id="calculator">7 + 3</gadget>
<output>10</output>

<result>10</result>