Theorem oveq12i

Description: Equality inference for operation value. (Contributed by NM, 28-Feb-1995) (Proof shortened by Andrew Salmon, 22-Oct-2011)

	Ref	Expression
Hypotheses	oveq1i.1	$$⊢A=B$$
	oveq12i.2	$$⊢C=D$$
Assertion	oveq12i	$$⊢AFC=BFD$$

Proof

Step	Hyp	Ref	Expression
1		oveq1i.1	$$⊢A=B$$
2		oveq12i.2	$$⊢C=D$$
3		oveq12	$$⊢\left(A=B\wedge C=D\right)\to AFC=BFD$$
4	1 2 3	mp2an	$$⊢AFC=BFD$$