SOLUTION: Tina can run 12 mi in the same time it takes her to bicycle 72 mi. If her bicycling rate is 20 mi/h faster than her running rate, find each rate.

Algebra ->  Expressions-with-variables -> SOLUTION: Tina can run 12 mi in the same time it takes her to bicycle 72 mi. If her bicycling rate is 20 mi/h faster than her running rate, find each rate.       Log On


   

Question 107632: Tina can run 12 mi in the same time it takes her to bicycle
72 mi. If her bicycling rate is 20 mi/h faster than her running rate, find each
rate.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Tina can run 12 mi in the same time it takes her to bicycle
72 mi. If her bicycling rate is 20 mi/h faster than her running rate, find each
:
Let s = T's running speed
then
(s+20) = T's cycling speed
:
Run time = cycling time
:
Time = Dist/speed
:
12%2Fs = 72%2F%28%28s%2B20%29%29
:
Cross multiply:
72s = 12(s+20)
:
72s = 12s + 240
:
72s - 12s = 240
:
60s = 240
:
s = 240/60
:
s = 4 mph is T's running speed
Then
24 mph is T's cycling speed
:
:
Check solution by find the times:
12/4 = 3 hrs
72/24 = 3 hrs, confirms our solutions