SOLUTION: A pharmacist is preparing a 300-milliliter solution of 25% alcohol. If she has 15% and 45% alcohol solutions in stock, how much of each must she use?

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Question 843683: A pharmacist is preparing a 300-milliliter solution of 25% alcohol. If she has 15% and 45% alcohol solutions in stock, how much of each must she use?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Volume:
1.A%2BB=300
Concentration:
15A%2B45B=25%28300%29
15A%2B45B=7500
2.A%2B3B=500
Subtract eq. 1 from eq. 2,
A%2B3B-A-B=500-300
2B=200
B=100
and from eq.1,
A%2B100=300
A=200
200ml of 15% and 100ml of 45%.