<PRE><B>Question 783860</B>
Let r = speed of boat in still water
let c = speed of the current


Direction___________speed__________time____________distance
UP__________________r-c____________5_______________145
DOWN________________r+c____________5_______________215


Most basically, r*t=d so we form two equations from the data table.

(r-c)5=145 and (r+c)5=215
5r-5c=145 and 5r+5c=215


Solve the system:
-----------------
5r-5c=145
-----------------
5r+5c=215
-----------------





----------------------------------------
Best way to begin solving the system is sum the lefthand members, sum the righthand members, and equate these.  You would then immediately find the value for r.  Continue any reasonable way to solve for and find c.</PRE>