2) [ ( 6x - 39) : 3 ] . 28 = 84
( 6x - 39 ) : 3 = 84 : 28
( 6x - 39 ) : 3 = 3
6x - 39 = 3 . 3
6x - 39 = 9
6x = 9 + 39
6x = 48
x = 48 : 6
x = 8
3) 20 - [ 7 . (x - 3) + 4 ] = 2
7 . (x - 3) + 4 = 20 - 2
7 . (x - 3) + 4 = 18
7 . (x - 3) = 18 - 4
7 . (x - 3) = 14
x - 3 = 14 : 7
x - 3 = 2
x = 2 + 3
x = 5