<PRE><B>Question 945690</B>
please show me the way you solve this problem. i am almost there. How many gallons of 5% acid solution should be mixed with 20 gallons of a 10% acid solution to obtain an 8% acid solution?
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let x=amt of 5% solution to mix
x+20=amt of combined 8% solution
..
5%x+10%*20=8%(x+20)
.05x+2=.08x+1.6
.03x=0.4
x=13 1/3 
amt of 5% solution to mix=13 1/3 gallon</PRE>