a car travels uphill at 30 km / hr and downhill at 90 km / hr . it goes 100 km uphill and 50 km downhill . find the average speed of the car ?
"avg speed = total distance / total time . total distance traveled = 100 + 50 = 150 km ; time taken for uphill journey = 100 / 30 = 10 / 3 ; time taken for down hill journey = 50 / 90 = 5 / 9 ; avg speed = 150 / ( 10 / 3 + 5 / 9 ) = 39 kmph answer : b"
divide(add(100, 50), add(divide(100, 30), divide(50, 90)))