So for starters each attack he performs will give him a boost of 18.7% per attack. that is what is being referred to when it says "calculated separately", it is about how it interacts with that starting 70% attack and defense buff the unit has. Next even though your SA boosts happened at different times, they are all still calculated together in the last part of the calculations. So in this case your Frieza launched 3 attacks in 1 turn. So his passive boost after he finished attacking was now a total of 126.1%, and then you calculate on the 2 defense raises from his super for that turn onto his defense stat. If I'm off with any of this hopefully someone will correct me.