The top right is the answer
47 days because If it’s half of the lake and doubles one more time then it would be the full lake
S=weight of soybean protein, C=weight of cornmeal protein.
Total weight of each protein is 0.18S+0.19C=0.17×360=61.2 lb.
Total weight of meal is S+C=360 lb. So S=360-C.
Therefore 0.18(360-C)+0.19C=61.2, 64.8-0.18C+0.19C=61.2, 0.01C=-3.6.
Clearly we would get a negative value for C. When you look at the question you will realise that there is a larger percentage of protein in the ingredients than there is in the mixture. The expected amount of protein in the mixture should be between 18% and 19%. Please check your figures.
I would say to check the 1st and 3rd
