If Ram and gohul can do a job in 10 days and 15 days independently, How many days would they take to complete the same job working simultaneously?  Select the correct option.
A) 10 B) 5 C) 8 D) 6 E) 13

Rationale: if total work is x . ram working rate = x / 10 per day . working rate of gohul = x / 15 per day . rate of work = ( x / 10 ) + ( x + 15 ) = 30 x / 5 x = 6 days the answer is option d
Answer: D