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?
<pre>Let Rico's speed be S
Then Luis' is: 3S
We then get: {{{72/S = 72/(3S) + 4}}} 
{{{216 = 72 + 12S}}} ------- Multiplying by LCD, 3S
{{{216 - 72 = 12S}}}
144 = 12S
S, or Rico's speed = {{{144/12}}}, or {{{highlight_green(matrix(1,2, 12, mph))}}}