Question 1129760
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P2 costs more per pound than P1; so to minimize cost they need to use the least amount of P2 that satisfies the constraints.<br>
The minimum allowed amount of P2 is 300 pounds.  That leaves 400 pounds for P1, and that amount is less than the maximum allowable amount.<br>
So the minimum cost is with 300 pounds of P2 and 400 pounds of P1.