Question 726836
VARIABLES TO USE
x = volume of water to use
y = volume of the salt solution to use
M = volume of resulting solution, 20 gallons
H = percent salt solution to use, 5%
T = percent salt solution result for mixture, 3%


MAKE EQUATIONS BASED ON PROBLEM DESCRIPTION
Account for salt.  Note very critically, the amount of water and salt solution are both unknown.  {{{highlight(Hy/(x+y)=T)}}}.

...AND, account for materials to use.  {{{highlight(x+y=M)}}}.


SOLVE THE SYSTEM
The only unknowns are x and y.  Solve this system for x and y.
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{{{highlight(Hy/(x+y)=T)}}}
{{{highlight(x+y=M)}}}
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COMPUTE VALUES OF x AND y
Substitute the known, given values into the formulas for x and y to find their values.