View Full Version : Systems of Equations word problem help

04-09-2007, 11:33 PM
A motorboat can go 8 miles downstream on a river in 20 minutes. It takes 30 minutes for this boat to go back upstream the same 8 miles. Find the speed of the current.

i know the answer is 4mi/h but i don't know how you get that ......
i just need help overall. i'm not even sure about what equations to put. for the system....

04-10-2007, 01:12 AM
REMEMBER THIS: speed = distance / time

m = motorboat speed, r = river speed (speed of current)

downstream: m + r = 8 / (1/3)
upstream: m - r = 8 / (1/2)

If you can't solve that, you need your teacher...