the speed of the boat in still water in 12 kmph . it can travel downstream through 39 kms in 3 hrs . in what time would it cover the same distance upstream ?
"still water = 12 km / hr downstream = 39 / 3 = 13 km / hr upstream = > > still water = ( u + v / 2 ) = > > 12 = u + 13 / 2 = 11 km / hr so time taken in upstream = 39 / 11 = 3.5 hrs answer : a"
divide(39, subtract(12, subtract(divide(39, 3), 12)))