SOLUTION: im stuck-please help-During rush hour, Fernando can drive 40 miles using the side roads in the same time that it takes to travel 30 miles on the freeway. If Fernando's rate on the

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Question 23840: im stuck-please help-During rush hour, Fernando can drive 40 miles using the side roads in the same time that it takes to travel 30 miles on the freeway. If Fernando's rate on the side roads is 7 mi/h faster than his rate on the freeway, find his rate on the side roads.
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Let the rate on the freeway be represented by x.
He drives 40 miles on the side road.
In same time he drives 30 miles on freeway.
Rate on the side road = 7+x
Rate on the freeway = x

Since 40 miles on side road and speed 7+x: expression = 40/(x+7)
Since 30 miles on freeway with the speed x: expression = 30/(x)

40%2F%28x%2B7%29+=+30%2F%28x%29 ---> cross multiply
30(x+7)=40x
30x+210=40x
210=10x
x=21

21+7=28

30(21+7)=40(7)
280=280

Hence, his speed on the freeway was 21mph, on the side road is; 28mph, with total distance traveled ---->280 miles.