i think it would recieve 3x exp multiplier since it takes 1.5 exp from being traded and 1.5 exp from lucky egg
50% exp boost(equivalent to 1.5x multiplier) from trade and 50% boost from lucky egg which means it might get 100% exp boost or equivalent to 2x exp multiplier.
im not just sure which one is right,
also as an addition,trained pokemons also give 1.5 exp boost,wild pokemons give no boost,so you gain more exp from pokemons that are from trainers.
Hope this helps.