<PRE><B>Question 526678</B>
by weight, 
A fertilizer is 20% potassium, 30% nitrogen, and 50% phosphorus. 
B fertilizer has percents of 10, 30, and 60, 
C fertilizer has percents of 0, 20, 80, respectively.
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How much of each must be mixed to get 200lb of fertilizer with percents of 12, 28.5, 59.5, respectively?
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Equations:
Potassium Eq: 0.20a + 0.10b + 0*c   = 0.12*200
Nitrogen Eq:: 0.30a + 0.30b + 0.20c = 0.285*200
Phosphorus Eq:0.50a + 0.60b + 0.80c = 0.595*200
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I used a matrix method to get:
A = 70 lbs.
B = 100 lbs
C = 30 lbs.
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Cheers,
Stan H.</PRE>