Lena drove to the mountains last weekend. there was heavy traffic on the way there, and the trip took 7 hours. when lena drove home, there was no traffic and the trip only took 5 hours. if her average rate was 18 miles per hour faster on the trip home, how far away does lena live from the mountains? do not do any rounding.

The distance between Lena's house and mountains is 315 miles.

Explanation:

We know that average speed is given by

Let the distance between the house of Lena and mountains be 'd'

Let the speed of trip towards mountains be

Since the average speed on the trip home is given as thus we have

Solving equations i and ii for 'd' we get

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