A) (x+450) - 3450=4000:80

b) 15 * (r-10) = 255

c) d * (2632:56) = 611

d) (1234+n) + 2140=52741

(х+450) - 3450=4000:80

(х+450) - 3450=50

х+450=3450+50

х+450=3500

х=3500-450

х=3050

15· (r-10) = 255

r-10=255:15

r-10=17

r=17+10

r=27

d· (2632:56) = 611

d·47=611

d=611:47

d=13

(1234+n) + 2140=52741

1234+n=52741-2140

1234 + n=50601

n=50601-1234

n=49367