Theorem rexnegd

Description: Minus a real number. (Contributed by Glauco Siliprandi, 2-Jan-2022)

	Ref	Expression
Hypothesis	rexnegd.1	$$⊢\phi \to A\in ℝ$$
Assertion	rexnegd	$$⊢\phi \to -A=-A$$

Proof

Step	Hyp	Ref	Expression
1		rexnegd.1	$$⊢\phi \to A\in ℝ$$
2		rexneg	$$⊢A\in ℝ\to -A=-A$$
3	1 2	syl	$$⊢\phi \to -A=-A$$