aqa alevel equillbria question help!!!

hello,

i would appreciate any help on this question!

2A + B ⇌ 3C + D
Justify the statement that adding more water to the equilibrium mixture will lower the amount of A in the mixture

the mark scheme says:
1 -- (All) conc fall: (ignore dilution)
OR Kc = mole ratio × 1/V
1 -- Equm moves to side with more moles
OR If vol increases, mole ratio must increase
1 -- To oppose the decrease in conc
OR To keep Kc constant

i understand that all of the concentrations will decrease, but i was stuck on how to get the 2 last points.

i learnt that//its a 'rule' in my head that for a change in concentration, you should not look at it in terms of number of moles, but simply on individual reactants or products, if that makes sense. I would only include moles in my answer if i was talking about pressure.

for example: a random q about conc - an increase in conc of product Q means the eqm shifts to the left, to decrease the conc of Q
and for pressure - an increase in pressure means the eqm will shift to the side with the least number of moles to oppose the change.

i dont understand how to apporach/ think about it when a change of conc happens to the whole thing, is what im trying to say.

thank you!! sorry if this was confusing......