ezhilkumarank wrote:

Question: A drives at a rate of m miles per hour from his home to the park. On his return trip he drives at a rate of n miles per hour. How far away from his home is the part if he spends a total of z hours in the car, making no stops along the way?

A) \(((n+z)/m) - (z/n)\)

B) \((m+n+z)/mn\)

C) \((mnz)/(m+n)\)

D) \((m+z)/mn\)

E) \(mz/n\)

Let the distance between home and park be \(d\).

From home to park A would need \(\frac{d}{m}\) hours and from park to home A would need \(\frac{d}{n}\) hours as A spent total of z hours for round trip then \(\frac{d}{m}+\frac{d}{n}=z\) --> \(d(\frac{m+n}{mn})=z\) --> \(d=\frac{mnz}{m+n}\).

Answer: C.

Bunuel -- you made it look so simple. I could not get my mind cranked up so quickly. Guess I have to practice more.