SOLUTION: How many gallons of a 21% acid solution and the 29% acid solution need to be mixed to make 8 gallons of a 26% acid solution?

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Question 927909: How many gallons of a 21% acid solution and the 29% acid solution need to be mixed to make 8 gallons of a 26% acid solution?
Answer by Techpriest(29) About Me  (Show Source):
You can put this solution on YOUR website!
Assuming we don't know the gallons of the 21% acid solution, we will express it as x.
Assuming we don't know the gallons of the 29% acid solution, we will express it as y.
In the assumptions, we are able to convey this equation.
+x+%2B+y+=+8+
+.21x+%2B+.29y+=+.26%288%29+
We are able to solve it through substitution by finding that y = 8 - x through the subtraction property of equality.
+.21x+%2B+.29%288-x%29+=+.26%288%29+ Substitution
+21x+%2B+29%288-x%29+=+26%288%29+ Since they are a percent, we will multiply all by 100.
+21x+%2B+232+-+29x+=+208+ Distribution
+-8x+%2B+232+=+208+ Combine Like Terms
+-8x+%2B+232+-+232+=+208+-+232+ Subtraction Property of Equality
+-8x%2F-8+=+-24%2F-8+ Division Property of Equality
+x+=+3+
Now we know that x is 3, we will plug-in the x for the y to find the value of y.
+y+=+8+-+x+
+y+=+8+-+3+
+y+=+5+
It takes 3 gallons of a 21% acid solution and 5 gallons of a 29% acid solution to make 8 gallons of a 26% acid solution.