SOLUTION: Bret started on a 80-mile bicycle ride at 15 miles per hour. After a time he became a little tired and slowed down to 10 miles per hour for the rest of the trip. The entire trip of

Question 885668: Bret started on a 80-mile bicycle ride at 15 miles per hour. After a time he became a little tired and slowed down to 10 miles per hour for the rest of the trip. The entire trip of 80 miles took
5 1/2 hours. How far had Bret ridden when he reduced his speed to 10 miles per hour?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = distance Bret had traveled
at mi/hr
Let = time spent traveling at
mi/hr
= distance Bret traveled at
mi/hr
= time spent traveling at
mi/hr
----------------
Equation for riding at 15 mi/hr:
(1)
Equation for riding at 10 mi/hr
(2)
(2)
(2)
---------------------
Substitute (1) into (2)
(2)
(2)
(2)
(2)
(1)
(1)
(1)
----------------
Bret had ridden 75 mi at 15 mi/hr
check:

----------------
(2)
(2)
(2)
OK

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