.
Let x be the speed of the person, in miles per hour.
Then the speed of the car is (x+3) mph, according to the condition.
The time walking 10 miles is hours.
The time driving 15 miles is hours.
Both times are the same --- so, you can write this equation
= .
Cross multiply; then simplify
10*(x+3) = 15x
10x + 30 = 15x
30 = 15x - 10x
30 = 5x
x = 30/5 = 6.
ANSWER. Walking speed is 6 miles per hour. Driving speed is 6+3 = 9 miles per hour.
Solved and explained.
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- Selected problems from the archive on a plane flying with and against the wind
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