Posted by **carl** on Wednesday, August 17, 2011 at 12:48am.

A boat can travel 114 miles upstream

in the same time that it can travel 186 miles downstream.

If the speed of the current is 6 miles per hour,

find the speed of the boat without a current.

- algebra -
**carl**, Wednesday, August 17, 2011 at 3:10pm
any help would be greatly appreciated :)

- algebra -
**Henry**, Wednesday, August 17, 2011 at 4:19pm
Speed of boat in still water = V mi/h.

Speed of boat upstream = V-6 mi/h.

Speed of boat down stream = V+6 mi/h.

(V-6)t = 114 mi.

Eq1: Vt - 6t = 114.

(V+6)t = 186 mi.

Eq2: Vt + 6t = 186.

Add Eq1 and Eq2 and get:

2Vt = 300,

Vt = 150.

In Eq1, substitute 150 for Vt:

150 - 6t = 114,

-6t = 114 - 150 = -36,

t = 6h.

In Eq2, substitute 6 for t:

6V + 6*6 = 186,

6V + 36 = 186,

6V = 150,

V = 25mi/h.

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