If two girls starting from same point, walking in the opposite directions with 7km/hr and 3km/hr as average speeds respectively. Then the distance between them after 12 hours is?  Select the correct option.
A) 120
B) 121
C) 122
D) 123
E) 124

Rationale: explanation : total distance = distance traveled by person a + distance traveled by person b = ( 7 ã — 12 ) + ( 3 ã — 12 ) = 84 + 36 = 120 km answer : a
Answer: A