My father is 33 years old and my son is 5 years old. A few years later, my father is three times as old as my son

My father is 33 years old and my son is 5 years old. A few years later, my father is three times as old as my son

33-5 = 28 years old Their age difference
28 △ 3-1 = 14 years old My son's age at that time
14-5 = 9 years old The number of years then and now
A: nine years later, my father is three times as old as my son