In each glycolytic pathway, glyceraldehyde 3-phosphate dehydrogenase produces 1 molecules of NADH as a result of reduction of NAD+.
Pyruvate dehydrogenase converts pyruvate to Acetyl CoA producing 1 molecule of NADH per pyruvate oxidized.
In Kreb's cycle, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, and malate dehydrogenase reactions produce 1 molecule of NADH each. Furthermore, succinate dehydrogenase reaction produces a single molecule of FADH2 per FAD reduced.
Since, we began with 2 molecules of glyceraldehyde 3-phosphate, we multiply the above figures by 2 and get a total of 10 NADH and 2 FADH2.
