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(a-b)+(c-d)

(a+b)-(c+d)

-(a+b)+(-c-d)

(-a-b)-(c+d)

а-b+c-da+b-c-d-a-b-c-d-a-b-c-d

(a - b) + (c - d) = a - b + c - d(a + b) - (c + d) = a + b - c - d-(a + b) + (-c-d) = -a - b - c - d(-a - b) - (c + d) = -a - b - c - d