This is a max fuel problem so you dont need MZFM (or so i was taught) - if you take the lowest of the landing and T/off ie the landing at 55'200 you need to do as follows:
55200 (rlm) - 34'900 (dom) - 16'600 (t/l) = 3700
Then add:
Taxy fuel 400 and Trip fuel = 12'700 (as these are burned off before t/o and during flight)
I may not explain it in the best way but most importantly it makes sense in my head. Hope his helps
DW