SOLUTION: Luis can drive 3 times as fast as Rico can ride his bicycle. If it takes Rico 4 hours longer than Luis to travel 72 miles, how fast can Rico ride his bicycle?

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Question 1022431: Luis can drive 3 times as fast as Rico can ride his bicycle. If it takes Rico 4 hours longer than Luis to travel 72 miles, how fast can Rico ride his bicycle?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
            rate      time       distance
LUIS        3r          t         72
RICO         r         t+4        72

R rate, T time, D distance;
Basic Travel Rate Rule is RT=D.

system%283r%2At=72%2Cr%28t%2B4%29=72%29
Solve the system.

Answer by MathTherapy(10555) About Me  (Show Source):
You can put this solution on YOUR website!

Luis can drive 3 times as fast as Rico can ride his bicycle. If it takes Rico 4 hours longer than Luis to travel 72 miles, how fast can Rico ride his bicycle?
Let Rico's speed be S

Then Luis' is: 3S

We then get: 72%2FS+=+72%2F%283S%29+%2B+4 

216+=+72+%2B+12S ------- Multiplying by LCD, 3S

216+-+72+=+12S

144 = 12S

S, or Rico's speed = 144%2F12, or highlight_green%28matrix%281%2C2%2C+12%2C+mph%29%29