Contingency .....

At Take-off your minimum fuel will be the sum of:

TRIP + CONTINGENCY + ALTERNATE + FINAL RESERVE

Contingency is there in case things don't go as planned .... the wind may be stronger ... you may not get the FL you planned on .... perhaps there was a change of runway which meant extra track miles ... HOWEVER, if all goes exactly to plan, you will not use contingency, hence the 'PLANNED' landing mass at DESTINATION will include (CONTINGENCY + ALTERNATE + FINAL RESERVE), and 'PLANNED' landing mass at alternate will include (CONTINGENCY + FINAL RESERVE).

Nautical Air Miles = Still Air Distance .... when there is NO wind, NAM will be the same as NGM.

For this question we can just use the formula:

NAM = NGM x (TAS/GS) .... (a version of this is given in CAP697 Section 4 page 16 para 5.2.d)