(- 1.8) + (+ 0.7) + (- 0.9) + 1.3 + (- 0.2) using the operation law of rational number addition

(- 1.8) + (+ 0.7) + (- 0.9) + 1.3 + (- 0.2) using the operation law of rational number addition

=-1.8+0.7-0.9+1.3-0.2
=-0.9