Ok here me out Cat and Rabbit – 10(CR) Dog and Rabbit – 20(DR) Dog and Cat – 24(DC) So : CR + DR = 30 (1 Dog, 1 Cat, 2 Rabbit) 30 – DC(24)= 6 6 = 2 Rabbit 6 : 2 = 3 Rabbit = 3 CR – 3 = 7 (Cat) DR- 3 = 17 (Dog) 17 + 7 + 3 =(10 + 17)= 27 Voila