a bout travels 280 miles downstream and back. The trip downstream took seven hours. The trip back took 14 hours. The speed of the boat in still water and the speed of the current

4 answers

since distance = speed * time, if the boat's speed is b and the stream's speed is s,

7(b+s) = 280
14(b-s) = 280

b+s = 40
b-s = 20

b=30, s=10
why is 1 equation plus and the other minus
Because (b+s) means the stream is working WITH the boat. And the current is helping the boats speed. But (b-c) means that the stream is working AGAINST the stream. So the stream is slowing the boats speed
how do you know b=30 and s=10