Theorem coeq1d

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

	Ref	Expression
Hypothesis	coeq1d.1	$$⊢\phi \to A=B$$
Assertion	coeq1d	$$⊢\phi \to A\circ C=B\circ C$$

Proof

Step	Hyp	Ref	Expression
1		coeq1d.1	$$⊢\phi \to A=B$$
2		coeq1	$$⊢A=B\to A\circ C=B\circ C$$
3	1 2	syl	$$⊢\phi \to A\circ C=B\circ C$$