A bus covered a distance of 250 km, partly at an average speed of 40 kmph and partly at 60 kmph. If the total time taken is 5 hours, then the distance covered at 40 kmph is  Select the correct option
A) 130 km  B) 120 km  C) 100 km  D) 140 km  E) none of these

Rationale: "let the partial distance covered at 40 kmph be x let the another partial distance covered at 60 kmph be ( 250 - x ) thus , x / 40 - ( 250 - x ) / 60 = 5 or , x / 40 + ( 250 - x ) / 60 = 5 or , ( 3 x + 500 - 2 x ) / / 120 = 5 or 500 + x = 600 x = 100 answer : c"
Answer: C