Solve for x in a Percentage Equation

Date: 2/5/96 at 17:56:20
From: Anonymous
Subject: word problem

Express as a function of x.

 i) The volume of water that must be added to 5L of antifreeze to 
    make a solution that is x percent antifreeze.

ii) The volume of antifreeze that must be added to 5L of water to 
make a solution that is x percent antifreeze

What are the domain and range of each function?

Graph the function.

Date: 6/18/96 at 13:31:1
From: Doctor Robert
Subject: Re: word problem

 i) The percent antifreeze of a solution is the amount of 
    antifreeze divided by the total volume of the solution.  
    Let W be the volume of water added to 5 liters of 
    antifreeze(assumed to be 100 percent antifreeze).  
    Then the fraction of antifreeze is

        x = 5/(5+W) 

    where the range is W>=0,and the domain is 0<x<1.

ii) x = A/(A+5) where A is the amount of pure antifreeze added 
    to 5 liters of water.  The domain of this function is 
    0 < = x < 1.  The range is A>= 0   

-Doctor Robert,  The Math Forum