is this math correct

[Freightman]

Let:

A = # of Aces left
C = # of non-Aces left
D = SUM(A, C)
E_A = Expectation of Ace underneath

A = 24
C = 288
D = 312
E_A = 10

EV = E_A(A/D)-(C/D)

= 10(24/(312 - 1.25*52)) - ((312 - 24 - 1.25*52)/(312 - 1.25*52))

= (240-223)/247


= 17/247

=0.068825911

Your numbers are wrong.
A=24
B=223
D=247
E/A=10

Remember, 1.25 decks have been played. What am I missing. I still come to 6.81%.