Calculer les expressions suivantes sans ut
la calculatrice.
a. A = (+ 7) + (+5) + (−8) + (−4)
b. B = (-5) + (+9) + (− 7) + (+3)
c. C = (-2) + (+9) + (+3) + (−8)
d. D = (+12) +(+5) + (-3) + (+1) + (−8)