Theorem 7m1e6

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

	Ref	Expression
Assertion	7m1e6	$$⊢7-1=6$$

Proof

Step	Hyp	Ref	Expression
1		6cn	$$⊢6\in ℂ$$
2		ax-1cn	$$⊢1\in ℂ$$
3		df-7	$$⊢7=6+1$$
4	1 2 3	mvrraddi	$$⊢7-1=6$$