SOLUTION: please help. im so stuck you walk on an indoor track and then you jog on an out door track. Your jogging speed is twice your walking speed. after one week you have walked 12 mil

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Question 842301: please help. im so stuck
you walk on an indoor track and then you jog on an out door track. Your jogging speed is twice your walking speed. after one week you have walked 12 miles and jogged 18 miles. if the total time spent walking and jogging is 7 hours. what is the walking and jogging speed.
thank you kind reguards
Mark
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = your walking speed in mi/hr
+2s+ = your jogging speed in mi/hr
Let +t+ = time spent walking in hrs
+7+-+t+ = time spent jogging in hrs
-----------------------------------
Equation fro walking:
(1) +12+=+s%2At+
Equation for jogging:
(2) +18+=+2s%2A%28+7+-+t+%29+
-----------------------
(2) +18+=+14s+-+2%2As%2At+
and
(1) +s+=+12%2Ft+
Substitute this into (2)
(2) +18+=+14%2A%2812%2Ft%29+-+2%2A%2812%2Ft%29%2At+
(2) +18+=+168%2Ft+-+24+
(2) +168%2Ft+=+42+
(2) +t+=+168%2F42+
(2) +t+=+4+
and
(1) +s+=+12%2Ft+
(1) +s+=+12%2F4+
(1) +s+=+3+
and
+2s+=+6+
The walking speed is 3 mi/hr
The jogging speed is 6 mi/hr
---------------------------
check:
(1) +12+=+s%2At+
(1) +12+=+3%2A4+
(1) +12+=+12+
and
(2) +18+=+2s%2A%28+7+-+t+%29+
(2) +18+=+6%2A%28+7+-+4+%29+
(2) +18+=+6%2A3+
(2) +18+=+18+
OK