a, (x - 29) - 11 = 0
(x - 29) = 0 + 11
x = 11 + 29 = 40
b, 231 + (321 - x) = 531
(321 - x) = 531 - 231
x = 321 - 300 = 21
c, (4 . x + 5) : 3 - 121 : 11 = 4
(4 . x + 5) : 3 - 11 = 4
(4 . x + 5) : 3 = 4 + 11
(4 . x + 5) = 15 : 3
4 . x = 5 - 5
x = 0 : 4 = 0
d, 131 . x - 941 = 27 . 23
131 . x - 941 = 210 = 1024
131 . x = 1024 + 941
x = 1965 : 131 = 15