Question Number 193821 by leandrosriv02 last updated on 20/Jun/23
Commented by talminator2856792 last updated on 21/Jun/23
$$\:\:−\left({a}\:+\:{b}\:−\:\mathrm{1}\right)\:+\:{a}\:+\:{b} \\ $$$$\:\:=\:{a}\:−{a}\:+\:{b}\:−{b}\:+\mathrm{1} \\ $$$$\:\:=\:\mathrm{0}\:+\:\mathrm{0}\:+\mathrm{1} \\ $$$$\:\:=\:\mathrm{1} \\ $$