Answer: Each booster has 11 cards and each premade deck has 41 cards
Step-by-step explanation: Assuming that every booster pack and every pre made deck has the same number of cards, you can have boosters = x and decks = y, if you have 3x+10y=443 for his allowance purchases and x+5y=216 for his birthday you can then solve by substitution
3x+10y=443
x+5y=216
subtract 5y
x=216-5y
substitute in to other equation
3(216-5y)+10y=443
distribute
648-15y+10y=443
subtract 648 and simplify
-5y=-205
divide by -5 (remember, a negative over a negative is a positive)
y=41
put y=41 into either equation
x+5(41)=216
x+205=216
x=11
y (decks) = 41
x (booster) = 11