ex:a+b+c+d;a-b+c-d;-(a-b)+c-d; pentru:
a)
a = - 0,31;
b = -0,74;
c = 1,44;
d = - 0,69

b)
a = - 22,8;
b= -43,2;
c = - 31,1;
d = 47,9;​