What if you have 10 commanders, each have different levels of research, how would you calculate the alliance level of research?
In this case you should divide the addition of each commanders' level by 5.
ex:
leader's melee attack: 30
1st officer's Melee Attack: 20
commander 1 - melee attack level 11
commander 2 - melee attack level 12
commander 3 - melee attack level 13
alliance melee attack: 4
Alliance Leader's Level + 1st Officer's Level/2 + Each of the Alliance Commanders' level/5 + Current Alliance Research Level
30 + 20/2 + (11+12+13)/5 + 4