2x + 3 = x - 6
2x - x = -6 - 3
x = -9
z + 4 - 3 = 2z
z - 2z = 3 - 4
-z = -1
z = 1
5 - 3y = 4 - 2y
-3y + 2y = 4 - 5
-y = -1
y = 1
7 - 3x = 4x - 9
-3x - 4x = -9 - 7
-7x = -16
7x = 16
x = 16/7
6a - 1 = 3a + 7
6a - 3a = 7 + 1
3a = 8
a = 8/3
10y - 3 = 5 + 3y
10y - 3y = 5 + 3
7y = 8
y = 8/7