Please explain how to do this?

Dear student,The oxygen carrying capacity of one gram of hemoglobin is 1.34 ml. With a hemoglobin content of 15 grams/dl blood and a normal hemoglobin oxygen saturation (SaO2) of 98%, arterial blood has a hemoglobin-bound oxygen content of 15 x . 98 x 1.34 = 19.7 ml O2/dl blood.So option c is correct.Regards.