Answer:
There are 5 pigs on Aaron's farm
Explanation:
1. Start with 40 animals
2. 1/10 of the animals are cows, so divide 40 by 10 and you will find that 4 of the animals are cows
3. 2/5 of the animals are chickens, so multiple 40 by 2 to get 80 and then divide 80 by 5 and you will find that 16 of the animals are chickens
4. Subtract the 4 cows and 16 chickens from the 40 total animals and you find there are 20 more animals that are neither cows nor chickens
5. Of the 20 remaining animals, 1/4 are pigs, so divide 20 by 4 and you will find that there are 5 pigs