De Morgan's laws of distributing negation over disjunction and conjunction states that
1.) ¬
(
a
∨
b
)
≡
(
¬
a
∧
¬
b
)
2.) ¬
(
a
∧
b
)
≡
(
¬
a
∨
¬
b
)
Thus, given the statement "The petting zoo is not closed and the animals are not being fed by people."
The statement is the conjunction of the negation of the statement "The petting zoo is closed" and the negation of the statement "The animals are being fed by people".
Using the first of De Morgan's laws above, we have that the equivalence of the statement given above is:
"It is not the case that the petting coo is closed or the animals are being fed by people".
