In Cliff's, it states that NADH results in 3 ATP molecules while FADH2 results in 2 ATP molecules, but in my biochemistry class we learned it as 2.5 ATPs for NADH and 1.5 for FADH2. I guess the value varies from source to source. I think as long as you know that NADH is a higher energy-rich molecule than FADH2, the specific numbers should not matter in the long run.
Aerobic respiration during the Kreb's Cycle makes 3 NADH, 1 FADH2, and 1 ATP from one acetyl CoA.