A man is four times as old as his son. In five years he will be only three times as old as his son. What is the man's present age?
Present age of man = 40 years
Let the present age of son be 'x' years.
Then, the present age of man is 4x years.
After 5 years,
Age of son = x+5
Age of man = 4x+5
age of man after 5 years = 3 times age of son after 5 years
Present age of man