Question 71686

Lex x=Amount of water to be added

Now we know that the amount of pure salt in water (0) plus the amount of pure salt in the original 5 gal of the 20% solution (0.20*5) has to equal the amount of pure salt in the final mixture ((5+x)*0.16).  So our equation to solve is:

(0.20)(5)=(5+x)(0.16)--get rid of the parens

1=0.8+0.16x  subtract 0.8 from both sides
1-0.8=0.8-0.8+0.16x  collect like terms
0.2=0.16x  divide both sides by 0.16
x=1.25 gal---------------------------------amount of water needed

CK

5+1.25=6.25
6.25(.16)=1
and 5(0.20)=1
1=1

Hope this helps----ptaylor