a) $130 - ( 100 + x ) = 25$
100 + x = 130 - 25
100 + x = 1054
$ x = 105 - 100$
$ x = 5$
b) 5 . ( x + 7 ) - 10 = $2^{3}$ . 5
5 . ( x + 7 ) - 10 = 8 . 5
5 . ( x + 7 ) = 40 + 10
5 . ( x + 7 ) = 50
x + 7 = 50 : 5
$ x + 7 = 10 $
$ x = 10 - 7$
x = 3
c) $7^{2}$ - 7 . ( 12 - x ) = 14
49 - 7 . ( 12 - x ) = 14
7 . ( 12 - x ) = 49 - 14
7 . ( 12 - x ) = 35
12 - x = 35 : 7
12 - x = 5
x = 12 -5
x = 7
$d) x - 48 : 16 = 37$
$ x - 3 = 37$
$ x = 37 + 3$
$ x = 40$