SOLUTION: Jenny can row 20 miles with the current in 2 hours, or 12 miles against the current in 3 hours. Find the rate of Jenny's boat in still water and the rate of the current.

Question 731646: Jenny can row 20 miles with the current in 2 hours, or 12 miles against the current in 3 hours. Find the rate of Jenny's boat in still water and the rate of the current.
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
rowing speed =x mph
current speed =y mph
against current 3 hours
with current 2 hours

Distance with current 20 miles distance against current 12
t=d/r against current (x-y)
12.00 / ( x - y )= 3.00

3.00 x - -3.00 y = 12.00 ....................1
with current (x+y)
20.00 / ( x + y )= 2.00
2.00 ( x + y ) = 20.00
2.00 x + 2.00 y = 20.00 ...............2
Multiply (1) by 2.00
Multiply (2) by 3.00
we get 2.00
6.00 x + -6.00 y = 24.00
6.00 x + 6.00 y = 60.00
12.00 x = 84.00
/ 12.00
x = 7 mph

plug value of x in (1) y
3 x -3 y = 12
21 -3 -21 = 12
-3 y = 12
-3 y = -9 mph
y = 3
rowing 7 mph
current 3 mph

RELATED QUESTIONS
With the current you can row 24 miles in 3 hours. Against the same current, you can row... (answered by mananth)

ronald can row 24 miles in 3 hours when he rows with the current. against the same... (answered by ikleyn)

With the current, you can row 9 miles in 2 hours. Against the current, your return trip... (answered by Alan3354)

A row boat traveled 12 miles in 2 hours against the current. It traveled 18 miles in the... (answered by solver91311)

motorboat traveling with the current can go 24 miles in 2 hours. Against the same... (answered by checkley77)

a boats crew rowed 9 miles down stream with a current, in 1.5hrs. the return trip... (answered by mananth)

Identify the variables, write a system of equations to solve (Problem on my exam study... (answered by Theo)

A boat'screw rowed 20 miles downstream, with the current, in 2 hours. The return... (answered by mananth)

paddling with a current a canoeist can travel 48 miles in 3 hours. against the current he (answered by mananth,Alan3354)