There are 4: oxaloacetate, malate, fumarate, and succinate.
(4/4)-(the square root of 4)-(the square root of 4)
4+4+4=12 12/4=3
(4 + 4 + 4) ÷ 4 = 12 ÷ 4 = 3.
alpha ketoglutarate