15.
(x - 36) : 13 = 4
x - 36 = 4 * 13
x - 36 = 52
x = 52 + 36
x = 88
---------------
18.
(57 + x) : 23 = 4
57 + x = 4 * 23
57 + x = 92
x = 92 - 57
x = 35
---------------
19.
(8 - x) : 12 = 4
8 - x = 4 * 12
8 - x = 48
-x = 40
x = -40
---------------
22.
(72 - x) * 9 = 27
72 - x = 27 : 9
72 - x = 3
-x = -69
x = 69
---------------
23.
4 * (75 - x) = 32
75 - x = 32 : 4
75 - x = 8
-x = -67
x = 67
---------------
24.
27401 : x - 119 = 398
27401 : x = 398 + 119
27401 : x = 517
x = 27401 : 517
x = 53
---------------
25.
17 * x - 48 : 4 = 90
17 * x - 12 = 90
17 * x = 90 + 12
17 * x = 102
x = 102 : 17
x = 6
---------------
26.
24590 - x * 25 = 815
-x * 25 = 815 - 24590
-x * 25 = - 23775
x = 23775 : 25
x = 951
---------------
27.
72 : 3 + x * 12 = 60
24 + x * 12 = 60
x * 12 = 60 - 24
x * 12 = 36
x = 36 : 12
x = 3