Question 934248
Let 3r= Luis's rate
     r= Carlos's rate
   t+2= Duration of Carlos traveled
     t= Duration of Luis traveled
  51mi= Total distance

Luis can drive 3 times as fast as Carlos can ride his bicycle. if it takes Carlos 2 hours longer than Luis to travel 51 miles
Distance = (rate)(time)
51=(3r)(t)
51=3rt
17=rt
17/r=t

51=(r)(t+2)
51=rt+2r
51-2r=rt
51-2r/r=t

17/r=51-2r/r
17=51-2r
2r=34
 r=17

Carlos's speed is 17mph.