There isnt enough information to solve the question, answer is E.
R-7=7 add the seven from both sides, leaving the r alone, because this is what you are trying to find. Thus the answer is r=14.
Let C be the number of cats and B be the number of birds.
Each cat has 4 legs while each bird has 2 legs. Thus,
4C + 2B = 22
2B = 22 - 4C
Each cat and each bird has 2 eyes
2C + 2B = 16
Substituting 2B
2C + 22 - 4C = 16
2C = 6
C = 3
2B = 22 - 4(3)
B = 5
2 cats and 5 birds
