Tìm số tự nhiên x biết: a) x : [(1800 + 600):30] = 560 : (315 – 35) b) [(250 – 25):15] : x

a) x : [(1800 + 600):30] = 560 : (315 – 35)

x : 80 = 2

x = 160

b) [(250 – 25):15] : x = (450 – 60) : 130

15:x=3

x = 15:3

x = 5

c) [(6x – 72) : 2 – 84].28 = 5628

(6x – 72) : 2 – 84=201

(6x – 72) : 2 = 285

6x -72 = 570

x = 107

d) 5x + x – 6 = 12

6x - 6 = 12

6x = 18

x = 3