Theorem eqtr2id

Description: An equality transitivity deduction. (Contributed by NM, 29-Mar-1998)

	Ref	Expression
Hypotheses	eqtr2id.1	|- A = B
	eqtr2id.2	|- ( ph -> B = C )
Assertion	eqtr2id	|- ( ph -> C = A )

Proof

Step	Hyp	Ref	Expression
1		eqtr2id.1	|- A = B
2		eqtr2id.2	|- ( ph -> B = C )
3	1 2	syl5eq	|- ( ph -> A = C )
4	3	eqcomd	|- ( ph -> C = A )