SOLUTION: tom drove 320 miles in 6 hours. his average speed for the first part of the trip was 60 mph and his average speed for the second part of the trip was 50 mph. how long did each part

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Question 1069175: tom drove 320 miles in 6 hours. his average speed for the first part of the trip was 60 mph and his average speed for the second part of the trip was 50 mph. how long did each part of the trip take him?
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.
tom drove 320 miles in 6 hours. his average speed for the first part of the trip was 60 mph and his average speed for
the second part of the trip was 50 mph. how long did each part of the trip take him?
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You can solve it using system of 2 equations in 2 unknowns 

t%5B1%5D+%2B+t%5B2%5D = 6,            (1)     (time equation
60%2At%5B1%5D+%2B+50%2At%5B2%5D = 320      (2)     (the distance equation)

where  t%5B1%5D is the time of driving at 60 mph,  t%5B2%5D is the time of driving at 50 mph,

or you can solve it using only ONE equation 

60*t + (6-t)*50 = 320,     (3)

where t is the time of driving at 60 mph.

For me, (3) is simpler:

60t + 300 - 50t = 320,

10t = 20,

t = 2.

Answer. 2 hours at 60 mph and 6-2= 4 hours at 50 mph.