Subject: mathqa
Question: a start walking from a place at a uniform speed of 6 kmph in a particular direction . after half an hour , b starts from the same place and walks in the same direction as a at a uniform speed and overtakes a after 1 hour 48 minutes . find the speed of b .
Option: 
A: 5.3 kmph
B: 4.7 kmph
C: 6.6 kmph
D: 7 kmph
Answer: C