SOLUTION: There are 2 vats of milk, one containing 25% protein and the other 40% protein. These two are to be mixed in order to get 12 liters of a 35% protein content milk. How many liters o

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Question 1005253: There are 2 vats of milk, one containing 25% protein and the other 40% protein. These two are to be mixed in order to get 12 liters of a 35% protein content milk. How many liters of each must be used?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = liters of 25% protein needed
Let +b+ = liters of 40% protein needed
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(1) +a+%2B+b+=+12+
(2) +%28+.25a+%2B+.4b+%29+%2F+12+=+.35+
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(2) +.25a+%2B+.4b+=+.35%2A12+
(2) +.25a+%2B+.4b+=+4.2+
(2) +25a+%2B+40b+=+420+
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Multiply both sides of (1) by +25+
and subtract (1) from (2)
(2) +25a+%2B+40b+=+420+
(1) +-25a+-+25b+=+-300+
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+15b+=+120+
+b+=+8+
and
(1) +a+%2B+b+=+12+
(1) +a+=+4+
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4 liters of 25% protein are needed
8 liters of 40% protein are needed
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check:
(2) +%28+.25a+%2B+.4b+%29+%2F+12+=+.35+
(2) +%28+.25%2A4+%2B+.4%2A8+%29+%2F+12+=+.35+
You can finish