Theorem 10m1e9

Description: 10 - 1 = 9. (Contributed by AV, 6-Sep-2021)

	Ref	Expression
Assertion	10m1e9	|- ( ; 1 0 - 1 ) = 9

Proof

Step	Hyp	Ref	Expression
1		9cn	|- 9 e. CC
2		ax-1cn	|- 1 e. CC
3		9p1e10	|- ( 9 + 1 ) = ; 1 0
4	3	eqcomi	|- ; 1 0 = ( 9 + 1 )
5	1 2 4	mvrraddi	|- ( ; 1 0 - 1 ) = 9