Answer:
Each booster pack has 9 cards, and each premade deck has 37 cards
Step-by-step explanation:
9 booster packs and 7 premade decks = 340 cards
4 booster packs and 1 premade deck = 73 cards
Multiply the bottom one by 7 to make the premade decks the same amount
9 booster packs and 7 premade decks = 340 cards
28 booster packs and 7 premade decks = 511 cards
511 - 340 = 171
28 - 9 = 19
19 booster packs is worth 171 cards
171 / 19 = 9
1 booster pack is worth 9 cards
So
9(cards) x 9(packs) = 81 cards
340 - 81 = 259 cards (in 7 premade decks)
259 / 7 = 37
1 premade deck is worth 37 cards
