Calculate the total time needed for a car travels 60 miles if the speed is 45 mph for 12 miles and 70 mph for the rest of the trip.

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First we will find the time need for the car travel each time of the time.

First, the car travels 12 miles at 45 mph

==> S = D/T ==> T = D/S = 12/45 = 4/15 hours

Then the car travels at 70 mph for the rest of the...

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First we will find the time need for the car travel each time of the time.

First, the car travels 12 miles at 45 mph

==> S = D/T ==> T = D/S = 12/45 = 4/15 hours

Then the car travels at 70 mph for the rest of the trip.

But the total trip is 60 miles.

==> D2 = 60 - 12 = 48 miles.

Then the car travels 58 miles at 70 mph

==> T2 = D2/S2 = 48/70 = 24/35 hours

Then the total time taken is T1 + T2

==> T= 4/15 + 24/35 = (28+ 72)/ 105 = 100/105 = 20/21 hours

20/21 hours.

Then the total time for the trip is 20/21 hour

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