SOLUTION: Here is the problem: A 70% acid solution is to be mixed with a 40% solution to get 90 gallons of a 50% solution. How many galens of each solution are needed? I'm not sure how to

Question 269893: Here is the problem: A 70% acid solution is to be mixed with a 40% solution to get 90 gallons of a 50% solution. How many galens of each solution are needed?
I'm not sure how to do this problem. I don't know how to get the two equations (because I think that's what needs to be done).
Thanks!
Answer by drk(1908) (Show Source): You can put this solution on YOUR website!
This is a mixture problem. Here is a table based on the given information.
solutions . . . . . . . . . % . . . . . . . . . .. gallon . . . . . . . . .. . %-gallon
70% . . . . . . . . . . . . .70. . . . . . . . . . . g. . . . . . . . . . . . . . .70g
40%. . . . . . . . . . . . . 40. . . . . . . . . . . 90 - g . . . . . . . . . . .3600 - 40g
mixture. . . . . . . . . . 50. . . . . . . . . . . 90 . . . . . . . . . . . . . .4500
From column 3 we get

subtract to get

divide to get

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you will need 30 gallons of 70% and 60 gallons of 40%.
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