Question 840401: At the beginning of a fundraiser walk, Barry and Dave are 30 miles apart. If they leave at the same time and walk in the same direction, Barry would overtake Dave in 15 hours. If they walked toward each other, they would meet in 3 hours. What are their speeds?
Rate Time Distance
Barry
Dave
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! At the beginning of a fundraiser walk, Barry and Dave are 30 miles apart.
If they leave at the same time and walk in the same direction, Barry would overtake Dave in 15 hours.
If they walked toward each other, they would meet in 3 hours.
What are their speeds?
Rate Time Distance
:
let b = Berry's walking speed
let d = Dave's
then
(b+d) = their relative speed, walking in opposite directions
and
(b-d) = their relative speed, walking the same direction
:
Write a distance equation for each scenario; dist = speed * time
3(b + d) = 30
15(b - d) = 30
Simplify divide the 1st equation by 3, the 2nd equation by 15
b + d = 10
b - d = 2
------------Addition eliminates d, find b
2b = 12
b = 6 mph is Berry's walking speed
:
Find d using b + d = 10
6 + d = 10
d = 4 mph is Dave's walking speed
:
:
You can see if that checks out using the original equations
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