# 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.

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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