Translate the problem to a system of equations, then solve using matrices.A merchant has coffee worth $40 a pound that she wishes to mix with 20 pounds of coffee worth $80 a pound to get a mixture that can be sold for $50 a pound. How many pounds of the $40 coffee should be used?
A. 40 lb
B. 30 lb
C. 80 lb
D. 60 lb
Answer: D
Mathematics
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