The main feature of the age problem is that the age difference between two people remains the same, but the multiple difference has changed.

The commonly used calculation formula is:

Age times = age difference ÷ (multiple-1)

Age a few years ago = small gift-multiplied by small age

Age in a few years = times its age-its age when it was very young now.

Father is 54 years old and son 12 years old. A few years later, the father was four times as old as his son.

(54-12) ÷ (4-1) = 42 ÷ 3 =14 (years old) → the age of the son in a few years.

14- 12=2 (year) →2 years later

Two years later, the father was four times older than his son.

Example 2: My father is 54 years old and my son is 12 years old. A few years ago, the father was seven times as old as his son.

(54-12) ÷ (7-1) = 42 ÷ 6 = 7 (years old) → My son's age a few years ago.

12-7=5 (years) →5 years ago

A: Five years ago, my father was seven times older than my son.

Ex. 3: The total age of Wang Gang's parents this year is 148 years old, and the difference between his father's age and his mother's age is more than three times that of his age and four years old. How old are Wang Gang's parents this year?

(148× 2+4) ÷ (3+1) = 300 ÷ 4 = 75 (years old) → father's age.

148-75=73 (years old) → mother's age

A: Wang Gang's father is 75 years old and his mother is 73 years old.

Or: (148+2) ÷ 2 =150 ÷ 2 = 75 (years old) 75-2=73 (years old)

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