Question 342339
Ava rode her bike from her house to her friends house averaging 16 km per hour. It turned dark so her friend drove her home at a rate of 80 km per hour. If Ava's  total traveling time was 3 hours, how far away did her friend live?


For this problem, we need to reealize that since the total time for the roundtrip was 3 hours, then time to travel to her friend's house, plus time to return home equals 3. Using D as the distance, the speed to the friend's house, and the speed on the return trip, this is expressed as: 


{{{D/16 + D/80 = 3}}}


Multiplying the equation by its LCD, 80, we get:


5D + D = 240


6D = 240


D, or distance to friend's house = {{{240/6}}} or {{{highlight_green(40)}}} kilometers.