SOLUTION: How many gallons of a 5% acid solution must be mixed with 5 gal of a 10% solution to obtain a 7% solution?

Question 67898This question is from textbook
: How many gallons of a 5% acid solution must be mixed with 5 gal of a 10% solution to obtain a 7% solution? This question is from textbook

Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
Let x = the required number of gallons of 5% acid solution.
You can write the equation from the problem description but first convert the percentages to their decimal equivalents.
5% of x + 10% of 5 = 7% of (x+5)
0.05(x) + 0.1(5) = 0.07(x+5) Simplify and solve for x.
0.05x + 0.5 = 0.35 + 0.07x Subtract 0.05x from both sides.
0.5 = 0.35+0.02x Subtract 0.35 from both sides.
0.15 = 0.02x Finally, divide both sides by 0.02
x = 7.5
You will need to add 7.5 gallons of 5% acid solution to 5 gallons of 10% acid solution to obtain 12.5 gallons of 7% acid solution.
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