a man ' s speed with the current is 21 km / hr and the speed of the current is 4.3 km / hr . the man ' s speed against the current is
"man ' s rate in still water = ( 21 - 4.3 ) km / hr = 16.7 km / hr . man ' s rate against the current = ( 16.7 - 4.3 ) km / hr = 12.4 km / hr . answer : d"
subtract(subtract(21, 4.3), 4.3)