They each expend less energy per kill, and face less risk, when hunting in a pack. That means that they can make more kills and get more sustinance. A pack of six wolves only needs to make four kills to get more sustinsnce each than six wolves each making an independent kill. Working as a pack also increases the reliability of hunting as they're more likely to make a kill each time they expend the considerable amount of energy it takes.

this is meaningless since we dont know how often they try and how often they succeed. it's the monthly moose ration that matters, not how much they can eat from a single kill.

Family groups. Kids old enough to hunt but not old enough to strike off on their own.

A single wolf may be able to kill a moose but a pack can definitely kill a moose. A single wolf might have to limit themselves to smaller moose while a pack can successfully take on a larger moose. A pack might have an easier time separating a single moose from the rest of the ... ~~mooses?~~ ... ~~meece?~~ ...moose herd.

Maybe the real moose is the friends you make along the way?