SOLUTION: A dairy needs 225 gallons of milk containing 5% butterfat. How many gallons each of milk containing 6% butterfat and milk containing 1% butterfat must be used to obtain the desired

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Question 1026247: A dairy needs 225 gallons of milk containing 5% butterfat. How many gallons each of milk containing 6% butterfat and milk containing 1% butterfat must be used to obtain the desired 225 gallons
Found 2 solutions by josgarithmetic, josmiceli:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
You can solve this using two variables, or you can handle a solution using only a single variable, as is shown in a helpful video from which you can learn:

Very typical two-part percentage mixure problem - only the quantities are changed while keeping the general form and similar application.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = gallons of 6% butterfat milk needed
Let +b+ = gallons of 1% butterfat milk needed
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(1) +a+%2B+b+=+225+
(2) +%28+.06a+%2B+.01b+%29+%2F+225+=+.05+
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(2) +.06a+%2B+.01b+=+.05%2A225+
(2) +.06a+%2B+.01b+=11.25+
(2) +6a+%2B+b+=+1125+
Subtract (1) from (2)
(2) +6a+%2B+b+=+1125+
(1) +-a+-+b+=+-225+
--------------------
+5a+=+900+
+a+=+180+
and
(1) +a+%2B+b+=+225+
(1) +b+=+225+-+180+
(1) +b+=+45+
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180 gallons of 6% butterfat milk needed
45 gallons of 1% butterfat milk needed
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(2) +%28+.06a+%2B+.01b+%29+%2F+225+=+.05+
(2) +%28+.06%2A180+%2B+.01%2A45+%29+%2F+225+=+.05+
(2) +%28+10.8+%2B+.45+%29+%2F+225+=+.05+
(2) +11.25+=+.05%2A225+
(2) +11.25+=+11.25+
OK