A woman complete a journey in 10 hours. She travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.
Choose the correct choice from the following answers
A) 334 km .
B) 216 km .
C) 314 km .
D) 224 km .
E) 544 km .

Rationale: "d 224 km . 0.5 x / 21 + 0.5 x / 24 = 10 - - > x / 21 + x / 24 = 20 - - > 15 x = 168 x 20 - - > x = ( 168 x 20 ) / 15 = 224 km ."
Answer: D