<PRE><B>Question 979390</B>
x=0.20 protein food.

(100+x)(0.18)=(100*0.12) + x(0.20) units are pounds-protein
18 + 0.18x=12 +0.20x
6 =0.02x
300 pounds=x   ANSWER

400 pounds of *0.18=72 pounds of protein
12 pounds in 100 pounds of food + 60 pounds in 300 pounds of 20%=72 pounds
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