There are 23 animals in the field. Some are cows and some are geese. There are 82 legs in all. How many of each animal are in the field?

There are 18 cows and 5 geese in the field. I found this purely by guess and check, but if we multiply 18 by 4 and 5 by 2, we get 72 and 10. Added up will equal to 82 legs.