(x+450)-3540=4000:80
(1234+n)+2140=52741

(x+450)-3540 = 4000:80

x+450-3540 = 50

x-3090 = 50

x = 50+3090

x = 3140

(1234+n)+2140 = 52741

1234+n+2140 = 52741

n+3374 = 52741

n = 52741-3374

n = 49367