According to the answer on page 207, I think MTOW shouldn't be 2791 kg, because 2791 without fuel is 2669 (2791 - ballast fuel 56 + burn-off 66 ) which is higher than ZFW limit 2630.
So the MTOW should be 2630 + minimum fuel req. 114 kg = 2744 kg
There is no need to do a ZFW check in this situation, because the ZFW is given as the starting point. On this occasion, the load sheet has been competed and the actual ZFW came to 2500kg. So if you are then going to use 2630kg in the calculation, you are actually answering a question that is different to the one being asked.
