SOLUTION: I have a word problem I need help with: Brett started on a 70-mile ride at 20 mph. After time he became tired and slowed down to 12 mph. The entire trip was 4 1/2 hours. How

Question 4135: I have a word problem I need help with:
Brett started on a 70-mile ride at 20 mph. After time he became tired and slowed down to 12 mph. The entire trip was 4 1/2 hours. How far did Brett travel when he slowed down t 12 mph.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Brett started on a 70-mile ride at 20 mph.
After time he became tired and slowed down to 12 mph.
The entire trip was 4 1/2 hours.
How far did Brett travel when he slowed down to 12 mph.
:
Let d = distance traveled when he slowed to 12 mph, (traveled at 20 mph)
then
(70-d) = distance traveled at 12 mph
:
Write a time equation; time = dist/speed
:
time at 20 mph + time at 12 mph = 4.5 hrs
+ = 4.5
Multiply by 60 to clear the denominators, resulting in:
3d + 5(70-d) = 60(4.5)
3d + 350 - 5d = 270
3d - 5d = 270 - 350
-2d = -80
d = +40 miles when he slowed to 12 mph
:
:
Check this find the total distance at each speed
40/20 = 2 hrs
30/12 = 2.5
---------------
total dist 4.5 hrs
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