SOLUTION: On an automobile trip,Jessa maintained a steady speed for 30 mins. Rush hour traffic slowed her speed by 40 kph for the last part of the trip.The entire trip, a distance of 38km to

Question 1132115: On an automobile trip,Jessa maintained a steady speed for 30 mins. Rush hour traffic slowed her speed by 40 kph for the last part of the trip.The entire trip, a distance of 38km took 1 hour and 15 mins. What was her speed during the first part of the trip? (use only one variable)(thanks in advance)
Answer by ikleyn(52797) (Show Source): You can put this solution on YOUR website!
.

The total time is  1 hour 15 minutes = 1.25 hours.


The first part of the trip at high speed took 30 minutes = 0.5 of an hour.


Hence, the second part of the trip took  1.25 - 0.5 = 0.75 of an hour.


Let x be the speed during the first part of the trip (the value under the question).


Then the first part of the trip was  0.5*x kilometers long (time multiplied by the speed).


The second part of the trip was  0.75*(x-40)  kilometers long.


Together, these two parts are the entire distance of 38 kilometers.


It gives you an equation


    0.5x + 0.75*(x-40) = 38   kilometers.


Simplify and solve for x:


    0.5x + 0.75x - 30 = 38

    1.25x = 30 + 38 = 68.

    x =  = 54.4 kilometers per hour.     ANSWER

Solved.

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