You are using the Max ZFW instead of Actual ZFW.
Maximum fuel allowed is the lowest of:
A.) Max TOW - Actual ZFW
B.) Max LW - Actual ZFW + Trip fuel
C.) Max Fuel Capacity
Actual ZFW = DOW (or DOM) + Traffic Load
= 35.5 + 14.5
= 50
Putting it all back into the above formula you'll find B.) gives you the lowest answer. E.g. 56.2 - 50 + 4.9 = 11.1 tonnes or 11,100 kg.
Thanks for asking that, I had to open up the books
