a) (9x – 23) : 5 = 2
(9x – 8) : 5 = 2
9x – 8 = 2 . 5
9x – 8 = 10
9x = 10 + 8
9x = 18
x = 18 : 9
x = 2
b) [34 – (82 + 14) : 13]x = 53 + 102
[81– (64 + 14) : 13]x = 125 + 100
[81– 78 : 13]x = 225
[81– 6]x = 225
75x = 225
x = 225 : 75
x = 3