Calculate the P(A-a)O2 for a patient with the following ABG…

Calculate the P(A-a)O2 for a patient with the following ABG results: pH 7.31, PaCO2 48 mm Hg, PaO2 50 mm Hg, SaO2 72% on a nonrebreathing mask at 12 L/min. (Assume the nonrebreathing mask is delivering approximately 70% oxygen.) **You do not have to type the units; type numerical value only for answer.