# Thread: Rational Functions problem: driver averaged 60mph on 300-mi trip....

1. ## Rational Functions problem: driver averaged 60mph on 300-mi trip....

Hi there!

There was a question on my homework worksheet that has me a little confused. I just don't know where to start. It goes like this :

"A driver averaged 60 miles per hour on a road trip from Santa Cruz to Los Angeles which is nearly 300 miles away. The average speed for going was x and the average speed for returning was y. (Hint : a 600 mile trip averaging 60 miles per hour means 10 total hours). Using Distance/Rate = Time formula, show that :
y = (30x) / (x-30)"

It says in the problem that I have to use the Distance/Rate=Time formula, but I am not sure how with this context. Do I have to start out with values and simplify it down to the one in the problem? If anyone can help, it would be greatly appreciated.

2. Originally Posted by kikithecat
Hi there!

There was a question on my homework worksheet that has me a little confused. I just don't know where to start. It goes like this :

"A driver averaged 60 miles per hour on a road trip from Santa Cruz to Los Angeles which is nearly 300 miles away. The average speed for going was x and the average speed for returning was y. (Hint : a 600 mile trip averaging 60 miles per hour means 10 total hours). Using Distance/Rate = Time formula, show that :
y = (30x) / (x-30)"

It says in the problem that I have to use the Distance/Rate=Time formula, but I am not sure how with this context. Do I have to start out with values and simplify it down to the one in the problem? If anyone can help, it would be greatly appreciated.
time required to go was = 300/x .... (Distance/Rate = Time formula)

time required for return was = 300/y .... (Distance/Rate = Time formula)

300/x + 300/y = 10

continue.....

3. Originally Posted by Subhotosh Khan
time required to go was = 300/x .... (Distance/Rate = Time formula)

time required for return was = 300/y .... (Distance/Rate = Time formula)

300/x + 300/y = 10

continue.....
Oh! I see. Now, would you use that equation to isolate y to get the formula from the problem? Thanks so much!

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