Question

Show that if A ⊂ B, then C – B ⊂ C – A.

Answer 1

Let A ⊂ B

To show: C – B ⊂ C – A
Let x ∈ C – B
⇒ x ∈ C and x ∉ B
⇒ x ∈ C and x ∉ A [A ⊂ B]
⇒ x ∈ C – A
∴ C – B ⊂ C – A