Question 887023
Same distance d both ways.
RT=D rate time distance.


_______________rate________time_________distance
UP_____________4___________{{{75/60}}}__________d
DOWN__________12___________t______________d


Simplify the UP time hours and compute d:


_______________rate________time____________distance
UP_____________4___________{{{1&1/4}}}__________d=4(5/4)=5
DOWN__________12___________t_________________d=5


The time going DOWN can now easily be computed as {{{t=5/12}}}


Total distance is BOTH WAYS, up and down {{{5+5=10}}} miles.
Total time in hours is {{{5/4+5/12=15/12+5/12=20/12=5/3}}} hours.


Average Speed, {{{10/(5/3)=(10*3)/5=highlight(6)}}}, miles per hour.