SOLUTION: please help me solve this problem: 1. A farmer has 100 galoons of 70% pure disinfectant. he wishes to mix it with disinfectant which is 90% pure in order to obtain 75% pure disi

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Question 393122: please help me solve this problem:
1. A farmer has 100 galoons of 70% pure disinfectant. he wishes to mix it with disinfectant which is 90% pure in order to obtain 75% pure disinfectant. how much of the 90% pure disinfectant must he use?
please show the solution, thank you!!
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

Let x represent  the total amount of the 90% solution

Question states***

Mixing to form (100+x) gallons of 75%

 .70*100gal + .90x = .75(100gal+x)

solving for x

          .15x = .05*100gal

             x = .05*100gal/.15

             x = 33 1/3 gal