x-180+214+318-109=1000
x=1000+180-214-318+109
x=1180-532+109
x=648+109
x=757
x - 180 + 214 + 318 - 109 = 1 000
x = 1 000 + 109 - 318 - 214 + 180 → aplic metoda mersului invers
x = 1 109 - 318 - 214 + 180
x = 791 - 214 + 180
x = 577 + 180
x = 757 → numarul
