(х + 450) -3540 = 4000: 80
(х + 450) -3540 = 50
х + 450 = 50 + 3540
х = 3590-450
х = 3140
(3140 + 450) -3540 = 4000: 80
50 = 50
(x+450)-3540=4000:80
x+450-3540=50
x-3090=50
x=50+3090
x=3140
(х + 450) -3540 = 4000: 80
(х + 450) -3540 = 50
х + 450 = 50 + 3540
х = 3590-450
х = 3140
(3140 + 450) -3540 = 4000: 80
50 = 50
(x+450)-3540=4000:80
x+450-3540=50
x-3090=50
x=50+3090
x=3140