$\text{A = a.(b-c) - b.(a+c) + c.(a+b) + 2021}$
$\text{A = a.b - a.c - b.a +b.c + c.a + c.b + 2021}$
$\text{A = [(a.b) - (b.a)] + [(a.c) - (c.a)] + [(b.c) - (c.b)] + 2021}$
$\text{A = 0 + 2021}$
$\text{A = 2021}$
$\text{B = (a + b) . (c - d) - (a - d) . (b + c) + (a - c) . (b + d)}$
$\text{B = a.c - a.d + b.c - b.d - a.b - a.c + b.d + c.d +a.b +a.d - b.c - c.d}$
$\text{B = 0}$
$\text{@Star}$