Question 975873: Julie recently drove to visit her parents who live 450 miles away. On her way there her average speed was 24 miles per hour faster than on her way home (she ran into some bad weather). If Julie spent a total of 20 hours driving, find the two rates.
Answer by josgarithmetic(39620)   (Show Source):
You can put this solution on YOUR website! Two-way drive, same distance d each way. Going, rate was r+k, using k as known and positive, but r as unknown. Trip returning, rate was r, an unknown. Total time driving was t hours. Find r, and use it to find r+k.
________________rate____________time____________distance
GOING___________r+k______________________________d
RETRG____________r_______________________________d
Total___________________________t________________2d
KNOWN VARIABLES
k,d, t
UNKNOWN: r
Solve for r.
Basic uniform rates rule for travel, RT=D.
________________rate____________time____________distance
GOING___________r+k_____________d/(r+k)___________d
RETRG____________r______________d/r_______________d
Total___________________________t________________2d
EQUATION FOR THE DESCRIPTION:
Solve for r. The other variables are already given.
Substitute the given values in the solution of r to evaluate.
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