The father is 36 years older than the son this year. Three years later, the father's age will be five times the son's age. How old is the son this year?
父亲今年比儿子大36岁，三年后父亲年龄是儿子年龄的5倍，请问今年儿子几岁？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<result>6</result>