Theorem coeq2d

Description: Equality deduction for composition of two classes. (Contributed by NM, 16-Nov-2000)

	Ref	Expression
Hypothesis	coeq1d.1	|- ( ph -> A = B )
Assertion	coeq2d	|- ( ph -> ( C o. A ) = ( C o. B ) )

Proof

Step	Hyp	Ref	Expression
1		coeq1d.1	|- ( ph -> A = B )
2		coeq2	|- ( A = B -> ( C o. A ) = ( C o. B ) )
3	1 2	syl	|- ( ph -> ( C o. A ) = ( C o. B ) )