A, B and C can do a job working alone in 6, 9 and 18 days respectively. They all work together for 1 day, then A and B quit. How many days C working alone will take to complete the remainder of the job?
The sum of present age of father and his son is 60 yrs. Six years ago, father's age was five times the age of the son. After 6 years, son's age will be?