In order to return her friend’s bicycle, a girl rides it to her friend’s house at a speed of 9 miles per hour. She then walks back home at a speed of 3 miles per hour. If the total time of the round...

In order to return her friend’s bicycle, a girl rides it to her friend’s
house at a speed of 9 miles per hour. She then walks back home at
a speed of 3 miles per hour. If the total time of the round trip was
1.5 hours, how far was her friend’s house?