I need help

Question

dan bought 9 baseball trading cards to add to his collection. the next day his dog ate half of his collection.there are now only 41 cards left. how many cards did dan start with

Answer 1

Hi Paris,

 

Dan is left with 41 cards.

These 41 cards represent 1/2 of his collection.

So this means he had 82 cards before the dog ate them (i.e. 41x2)

 

But the day before he bought 9 cards to add to his collection.

So the day before he only had 73 cards (82-9)

 

Expressed mathematically, we have

(x+9)/2=41

 

Solving for x we would first multiply by 2

x+9 = 82

 

Subtract 9 from both sides

x = 73

 

So Dan started with 73 cards.