(168 - a) : 5 = 12
168 - a = 60
a = 168 - 60 = 108
_____________
(236 - a) x 10 = 1800
236 - a = 180
a = 236 - 180 = 56
_______________
1973 - 426: a = 1902
1973 - 1902 = 426 : a
71 = 426 : a
a = 6
____________
1706 + a x 13 = 2031
a x 13 = 2031 - 1706 = 325
a = 25
_____________
967 : (5a + 1) = 10 rest 7
967 = 10 (5a + 1) + 7
960 = 10 (5a + 1)
96 = 5a + 1
96 - 1 = 5a
95 = 5a
a = 95 : 5 = 19
_____________
20 : a x 35 = 700
a = 700 : (20 x 35) = 700 : 700 = 1
_____________
16 x a : 8 = 32
2 x a = 32
a = 32 : 2 = 16
_____________
a : 19 x 6 = 144
a : 19 = 144 : 6 = 24
a = 19*24 = 456
_____________
a : 13 x 9 = 819
a : 13 = 819 : 9 = 91
a = 13 x 91 = 1183
_____________
16 x 12 : a = 6
a = 16 x 12 : 6 = 32
___________
(4b + 3) : 47 = 19 rest 6
4b + 3 = 19x 47 + 6
4b = 896
b = 224
