A father is now three times as old as his son. Five years back, he was four times as old as his son. The age of the son (in years) is

A. 12 B. 15
C. 18 D. 20

• 15 years
  
  If father's age is F and son's age is S, then
  F=3S
  and
  F-5 = 4*(S-5)
  3S-5 =4S-20
  S=15
  F=45 years
  
  5 yrs earlier , son's age = 10 yrs and father's age = 40 yrs.
• 12 years agoHelpfull: Yes(4) No(0)
• LET SON'S AGE=X THEN FATHER'S AGE=3X
  3X-5=4(X-5)
  THEN X=15 I.E.,SON'S AGE..
  ANS:B
• 9 years agoHelpfull: Yes(0) No(0)