SOLUTION: This word problem is difficult. Nancy drives 20mph faster than her father, Greg. In the same time that nancy travels 180 miles,her father travels 120 miles. find their speeds. I ne

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: This word problem is difficult. Nancy drives 20mph faster than her father, Greg. In the same time that nancy travels 180 miles,her father travels 120 miles. find their speeds. I ne      Log On


   

Question 554322: This word problem is difficult. Nancy drives 20mph faster than her father, Greg. In the same time that nancy travels 180 miles,her father travels 120 miles. find their speeds. I need help.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Start with:
d+=+r%2At d = distance, r = rate/speed, and t = time of travel.
For Nancy: d%5B1%5D+=+r%5B1%5Dt
For Greg: d%5B2%5D+=+r%5B2%5Dt The time, t, is the same in both cases.
d%5B1%5D+=+180 and d%5B2%5D+=+120
r%5B1%5D+=+r%5B2%5D%2B20
180+=+%28r%5B2%5D%2B20%29t
180+=+r%5B2%5Dt%2B20t
120+=+r%5B2%5Dt Subtract this equation from the one above.
60+=+20t Divide by 20.
t+=+3hours.
180+=+r%5B1%5D%2A3
r%5B1%5D+=+60MPH. This is Nancy's speed.
120+=+r%5B2%5D%2A3
r%5B2%5D+=+40MPH. This is Greg's speed.