$6:11$ - $4:43$ = $1$ hour $39$ minutes 
We left for a summer camp at $4:32$ PM and got to our destination at $6:11$ PM. How long did we travel? (Adapted from 2015 Math Kangaroo Problem, Level 1--2, Question \#24) 

a) $1$ hour $39$ minutes 
b) $2$ hours $39$ minutes 
c) $2$ hours $21$ minutes 
d) $1$ hour $21$ minutes 
e) $39$ minutes 