Problema Solution
Solve the problem by setting up and solving an appropriate algebraic equation.
Bret started on a 70-mile bicycle ride at 16 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 70 miles took 4 1/2 hours. How far had Bret ridden when he reduced his speed to 12 miles per hour?
Answer provided by our tutors
Let d= distance traveled at 16 MPH
(70-d) = Distance traveled at 12MPH
time= Distance / Speed <----Common formula you should know.
So we know:
(d/16)+(70-d)/12 = 4.5
Find common denominators:(192)
(12d/192)+16(70-d)/192 = 4.5
Add them up:
12d/192 + (1120-16d) = 4.5
(12d+1120-16d)/192 = 4.5
Solve:
(-4d+1120)/192=4.5
-4d+1120 = 864
-4d=-256
d= 64
Traveled 64 Miles at 16MPH and 6 Miles at 12MPH