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 $75 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 $5.50 per pound, which processing method should be used? b) At what selling price for the metal would the 2 processes be equally economical?