Answer:
POKEMON YEAH!
Okay, so you first want to take 2485, and subtract it from 4500, because that is the amount of money he has already collected.
4500 - 2485 = 2015
Now you need to find out how many time you can multiply 155, to get 2015, or higher. In this case, I am just gonna divide:
2015/155 = 13
It will take him 13 more weeks to have enough for the Pokemon cards!
Explanation:
Hope it helps! =D