1) (a- b) + (c- d)=
а-b+c-d;////
2) - (- a + b) - (- c - d)=
a-b+c+d;////
3) (a + b) – (c + d)=
a+b-c-d;////
4) – (a + b) + (- c - d)=
-a-b-c-d;///
5) – (a - b) – (c + d)=-a+b-c-d;////
Вариант2.
1) (a - b) - (c- d)=a-b-c+d;///
2) - (- a - b) + (- c - d)=
a+b-c-d;///
3) (a + b) + (- c + d)=
a+b-c+d;////
4) – (a - b) + ( c - d)=
-a+b+c-d;////
5) – (a + b) – (c + d)=
-a-b-c-d