Theorem 8m1e7

Description: 8 - 1 = 7. (Contributed by AV, 6-Sep-2021)

	Ref	Expression
Assertion	8m1e7	$$⊢8-1=7$$

Proof

Step	Hyp	Ref	Expression
1		7cn	$$⊢7\in ℂ$$
2		ax-1cn	$$⊢1\in ℂ$$
3		df-8	$$⊢8=7+1$$
4	1 2 3	mvrraddi	$$⊢8-1=7$$