Game does not allow to open more than 200 packs at once ( pfffff :D ) so it will be 200+200+175
This is what you see, when opening packs:
Here are some statistics from monstermarket:
Peakmonsters:
Spent 1 218 250 DEC for packs+potions ( + got some cashbacks ). I must have 1.84 Gold+Legendary cards every 575 packs, but i wasn't lucky enough to get second G+L, well This is the way :D