Answer:
3 cows and 27 chickens?
Explanation:
x is the number of cows and y is the number of chicken
x + y = 30
cow has 4 legs and chicken has 2 legs therefore
4x + 2y = 66
simultaneously,
x + y = 30 ⇒ x = 30 - y
substitute x = 30 - y in 4x + 2y = 66
4(30 - y) + 2y = 66
120 - 4y + 2y = 66
120 - 2y = 66
-2y = 66-120
-2y = -54
y = -54/-2
y = 27
x = 30 - 27
x = 3