a man can swim in still water at 12 km / h , but takes twice as long to swim upstream than downstream . the speed of the stream is ?
"m = 12 s = x ds = 12 + x us = 12 + x 12 + x = ( 12 - x ) 2 12 + x = 24 - 2 x 3 x = 12 x = 4 answer : e"
divide(12, const_3)