Question 86518: During rush hour, Bill can drive 15 miles using the side roads in the same time that it takes to travel 10 miles on the freeway. If Bill's rate on the side roads is 8 mi/h faster than his rate on the freeway, find his rate on the side roads
A)18
B)26
C)16
D)24
Answer by Nate(3500)   (Show Source):
You can put this solution on YOUR website! During rush hour, Bill can drive 15 miles using the side roads in the same time that it takes to travel 10 miles on the freeway. If Bill's rate on the side roads is 8 mi/h faster than his rate on the freeway, find his rate on the side roads
We'll use the: Rate * Time = Distance
But, we must suit the equation to time (time is equal here): Time = Distance / Rate
Side Roads:
Distance = 15
Rate: 8 + r
~ 15 / (8 + r) = distance / rate
Freeway:
Distance = 10
Rate: r
~ 10 / r = distance / rate
~ Time = Time ... the time was equal
~ distance / rate = distance / rate
~ 15 / (8 + r) = 10 / r
~ 15r = 80 + 10r
~ 5r = 80
~ r = 16
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