SOLUTION: a car travels at a constant speed for 450km if the average speed was increased by 15km/h the journey would have taken 90 min less find speed of car

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Question 1042715: a car travels at a constant speed for 450km if the average speed was increased by 15km/h the journey would have taken 90 min less find speed of car
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620) (Show Source):
You can put this solution on YOUR website!
a car travels at a constant speed for 450km if the average speed was increased by 15km/h the journey would have taken 90 min less find speed of car
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A car travels at a constant speed for r kilometers per hour. If the average speed was increased by k, the journey would have taken h hours. Find speed of car.

Units will be in kilometers, kilometers per hour, and hours, units.
Basic Travel Rates Rule to relate RATE, TIME, and DISTANCE, using R, T, and D, is RT=D.

These variables assignments are made:

Solve for k, and for d.

RATE TIME DISTANCE AS DONE r t d IF FASTER r+k t-h d

Can you solve this system? It is nonlinear, and allows for two substitutions in the steps.

Answer by MathTherapy(10552) (Show Source):
You can put this solution on YOUR website!

a car travels at a constant speed for 450km if the average speed was increased by 15km/h the journey would have taken 90 min less find speed of car

Let speed of car be S
Then hypothetical speed = S + 15
We then get the following TIME equation: _____
450(2)(S + 15) = 450(2S) + 3S(S + 15) --------- Multiplying by LCD, 2S(S + 15)

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Factor the trinomial on the left to solve for S: the speed of the car. You should get