Question 495923: two cars leave from the same location and go in opposite directions. The north bound car travels 15mph slower than the south bound car. After 6 hours they are 630 miles apart. Find the rate of each car.
How would i set this equation up to find the value of (X) if (X) is the rate of the cars
Answer by ptaylor(2198)   (Show Source):
You can put this solution on YOUR website! Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r
Now you need to think about this a little. The cars are traveling at different rates, so X can't be the "rate of the cars". But X can be the rate of one of the cars:
Let X=rate of north-bound car
Then X+15=rate of south-bound car
Distance north-bound car travels after 6 hours=X*6
Distance south-bound car travels after 6 hours=(x+15)*6
Now we are told that these two distances add up to 630 mi, soooo
6X+6(X+15)=630 get rid of parens
6X+6X+90=630 subtract 90 from each side
12X=540
X=45 mph---------------------------rate of north-bound car
X+15=45+15=60 mph----------------------rate of south-bound car
CK
45*6+60*6=630
270+360=630
630=630
Another way:
We know the cars are separating at the rate of X+X+15mph=2X+15 mph
in 6 hours they have traveled (2X+15)*6=12X+90 miles and we are told that this equals 630 mi, sooo
12X+90=630----same as before
Hope this helps---ptaylor
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