Theorem eqtr2di

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

	Ref	Expression
Hypotheses	eqtr2di.1	|- ( ph -> A = B )
	eqtr2di.2	|- B = C
Assertion	eqtr2di	|- ( ph -> C = A )

Proof

Step	Hyp	Ref	Expression
1		eqtr2di.1	|- ( ph -> A = B )
2		eqtr2di.2	|- B = C
3	1 2	eqtrdi	|- ( ph -> A = C )
4	3	eqcomd	|- ( ph -> C = A )