Theorem elun2

Description: Membership law for union of classes. (Contributed by NM, 30-Aug-1993)

	Ref	Expression
Assertion	elun2	$$⊢A\in B\to A\in \left(C\cup B\right)$$

Proof

Step	Hyp	Ref	Expression
1		ssun2	$$⊢B\subseteq C\cup B$$
2	1	sseli	$$⊢A\in B\to A\in \left(C\cup B\right)$$