A family travelled for 12 hours. They covered the first half of the distance at 35 kmph and remaining half of the distance at 40 kmph. Find the distance travelled by the family? Choose the correct choice from the following choices.
A) 270 km B) 890 km C) 684 km D) 320 km E) 560 km

Rationale: let the distance travelled be x km . total time = ( x / 2 ) / 35 + ( x / 2 ) / 40 = 12 = > x / 70 + x / 80 = 12 = > ( 8 x + 7 x ) / 560 = 12 = > x = 560 km answer : e
Answer: E