SOLUTION: Mr. Anderson drives his family to a picnic ground 60 miles from his home. When he returned home that evening he increased his his average speed 9 miles per hour compared to tue rat

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Question 827156: Mr. Anderson drives his family to a picnic ground 60 miles from his home. When he returned home that evening he increased his his average speed 9 miles per hour compared to tue rate on the way to the picnic. He reduced his return time by 20 minutee. What was his average speed going and returning?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
The rate goingTo and the time goingTo are unknown, and all other quantities are either known or described in relation to the unknown variables.

Let r = rate GoingTo, and t = time in hours GoingTo the picnic.


WhichWay________rate______time__________distance
GoingTo__________r__________t___________60
Returning________r+9______t-1/3_________60

The main rule about uniform rate, travel or movement is r*t=d, r for rate, t for time, d for distance.

EQUATIONS:
GoingTo: rt=60
ReturningFrom: %28r%2B9%29%28t-1%2F3%29=60
'
Two equations in two unknown variables. You take the rest of the work.