Question 242150
How many gallons of cream that is 30% butterfat must be mixed with milk that is 3% butterfat to make 45 gallons that are 12% butterfat? 
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m + c = 45
0.03m + 0.3c = 45*0.12 = 5.4
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m + c = 45
3m + 30c = 540
m + 10c = 180
m + c = 45
------------- Subtract
9c = 135
c = 15
m = 30