Răspuns :
1) a+b = -7 s i c = -3 => a+(b+c) = (a+b) + c = (-7)+(-3) =-7-3=-10
2) a = -2 si b+c = -19 => a+(b+c) = -2 + (-19) = -2-19 = - 21
a+b= -10 si c+d = 124 => (a+b)-(c+d) = -10 - (+124) = -10-124 = - 134
2) a = -2 si b+c = -19 => a+(b+c) = -2 + (-19) = -2-19 = - 21
a+b= -10 si c+d = 124 => (a+b)-(c+d) = -10 - (+124) = -10-124 = - 134