SOLUTION: Two cars leave a restaurant at the same time and travel in opposite directions. At the end of 3 hours, they are 300 miles apart. Find the rate of the slower car if one car travels

Algebra.Com
Question 110306This question is from textbook
: Two cars leave a restaurant at the same time and travel in opposite directions. At the end of 3 hours, they are 300 miles apart. Find the rate of the slower car if one car travels at a rate 20 miles per hour faster than the other. I know the equation r=d/t, but how do you plug the info in when there are two parts. Thanks for your help! This question is from textbook

Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!
If they are 300 miles apart after 3 hours, then their speeds must add to 100 mph. . So if one car is 20 mph faster than the other, let r = the slower car's rate, and r + 20 = the faster car's rate. Since the sum of the rates must be 100, we can write
:



, which is the rate of the slower car.
:
Check:
If the slower car's rate is 40 mph, the faster car's rate must be 40 + 20 = 60 mph.
:
Using , the slower car must have traveled 40 * 3 = 120 miles, and the faster car must have traveled 60 * 3 = 180 miles. 120 + 180 = 300. Check!
RELATED QUESTIONS

Two cars, one traveling 8 miles per hour faster than the other, start at the same time... (answered by JulietG)
Two cars start at the same time from the same point and travel in opposite directions.... (answered by Mathtut)
Two cars start at the same time from the same point and travel in opposite directions.... (answered by Alan3354)
Two cars, one traveling 10 mph faster than the other, start at the same time from the... (answered by ewatrrr)
Two cars leave a restaurant at the same time and travel in opposite directions. One... (answered by stanbon)
Two cars, one traveling 10 mph faster than the other car, start at the same time from the (answered by TimothyLamb,Danielshinmath)
Two planes leave the same airport the same time and travel in opposite directions, one at (answered by TimothyLamb)
Two cars leave a restaurant and travel in opposite directions. One travels at a rate of (answered by checkley79)
Two cars leave the airport at the same time and travel in opposite directions. If one car (answered by mananth)