Given: Age after 8 years = 3 × Present age Concept used: Using concept of linear equation. Calculation: Let the present age of man be x years Let n years after the age will be 5 times of present age. According to the question, Age after 8 years = 3 × Present age ⇒x+8=3x ⇒2x=8 ⇒x=4 After n years = 5 × Present age ⇒x+n=5x ⇒4+n=20 ⇒n=16 years ∴ After 16 years the age will be 5 times of present age.