distance = speed * time
9 = (v-9) t
20 = (v+9) t
but t is the same
so
9/(v-9) = 20/(v+9)
9(v+9) = 20(v-9)
9 v + 81 = 20 v - 180
11 v = 261
v = 23.7
a boat moves 9 kilometers upstream in the same amount of time it moves 20 kilometers downstream. If the rate of the current is 9 kilometers per hour. Find the rate of the boat in still water
1 answer
1 answer