Sea water contains 2.1 pounds of magnesium per ton. By using processing method A, 85% of the metal can be recovered at a costs of P75 per ton of water pumped and processed. If process B is used, 70% of the metal is recovered at a costs of only $6.00 per ton of water pumped and processed. The two processes are substantially equal as to investment cost and time requirements. a) If the extracted metal can be sold for P5.50 per pound, which processing method should be used? b) At what selling price for the metal would the 2 processes be equally economical?