3. He started out with 36 cards and then added 372 more. So now he has a total of 408 cards. He has 5 folders each with the same number of cards. 408 divided by 5 = 45 with three left over.
I just kind of sat here playing with numbers i dont really know a shortcut but the answer is 10 chickens and 15 rabbits 10*2= 20 each chicken has two legs so thats 10 heads 20 legs 15*4=60 each rabbit has four legs so thats 15 heads 60 legs 15+10=25 heads 20+60=60 legs