Question

Luis can drive 3 times as fast as rico can ride his bike. If it takes rico 4 hours longer than Luis to travel 72 miles, how fast can ricoride his bike

Answer 1

Let Rico's speed be S
Then Luis' is: 3S
We then get: seventy-two over s equals seventy-two over three s plus four 
216=72+12s  Multiplying by LCD, 3S
216-72=12s
144 = 12S
S, or Rico's speed would be 144 over 12 or 12mph