Kara hiked 14 km at 4 km/h and then hiked another 12 km at 5 km/h .

how long did the hike last?

a.
5 hours

b.
5.9 hours

c.
8.4 hours

d.
116 hours

So hiked 4km 1 hour = 60 min. 
               14 km x
             
               x = 14*60/4 = 14*15 = 210 min.  = 3 h 30 min. 

and so again hiked 15 km by 5km/h

 so 5km 1 hour =60 min. 
     12 km x
 
       x = 12*60/5 = 12*12 = 144 min = 2 h 24 min.  

so total 3 h 30 min. +2 h 24 min. = 5 h 54 min.