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# Pre Calc

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Two cars start out together from the same place. They travel in opposite​ directions, with one of them traveling

5 miles per hour faster than the other. After three hours, they are 423 miles apart. How fast is each car​ traveling?

The slow car travels at ____ MPH and the faster car travels at ____ MPH.

Feb 3, 2020

#1
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Since there are two unknown you need two equations. X = the fast car. Y = the slower car.

y = x + 5

since the faster car is 5 mph faster

3x + 3y = 423

since they travel 3 hours.

then we have to substitute the value of y into the second equation.

3x + 3(x + 5) = 423

divide both sides with 3

2x + 5 = 141

2x = 136

x = 68

Now that we now x we can use the first equation to get y.

y = 68 + 5

y = 73

Answer: The slow car travels at 68 MPH and the faster car travels at 73 MPH.

Feb 3, 2020
#2
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speed 1 = x

speed 2 = x+5

rate * time = distance

(x   +    x+5  ) * 3 hr = 423 m

x = 68           the other car is  73 m/hr

Feb 3, 2020