The sum of the present ages of a father and his son is 47 years. Six years ago, father's age was four times the age of the son. After 6 years, son's age will be:	Pick one: A) 13 B) 15 C) 17 D) 19 E) 21
Let the present ages of son and father be x and (47 - x) years respectively.   Then, (47 - x) - 6 = 4(x - 6)   41 - x = 4x - 24   x = 13   The son's age after 6 years will be 19.   The answer is 19.
<result>D</result>
The sum of the present ages of a father and his son is 47 years. Six years ago, father's age was four times the age of the son. After 6 years, son's age will be: