SOLUTION: Bret started on a 80-mile bicycle ride at 19 miles per hour. After a time he became a little tired and slowed down to 12 miles per hour for the rest of the trip. The entire trip of

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Question 351364: Bret started on a 80-mile bicycle ride at 19 miles per hour. After a time he became a little tired and slowed down to 12 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 12 miles per hour?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
D=RT
T=D/R
5.5=(X/19)+(80-X)/12)]
5.5=(12X+19(80-X)/19*12
5.5=(12X+1,520-19X)/228
5.5=(-7X+1,520)/228 CROSS MULTIPLY.
-7X+1,520=228*5.5
-7X=1254-1,520
-7X=-266
X=-266/-7
X=38 MILES FOR THE 19 MPH LEG.
80-38=42 MILES FOR THE 12 MPH LEG.
PROOF:
5.5=38/19+42/12
5.5=3+2.5
5.5=5.5