Variables 
                2x - 1x = 5+7
12
2x + 5 = 1X
-5
3x = 21
7
7x + 3 = 2x + 13
x + 11 - 2 = 10
5x - 3x + 4 = 1x - 5
-9
13x - 9x + 20 = 30 + 2
3
-20x + 15 = 2 - 16x + 11
1/2
x - 4 + 4 = 6
6
-6
7x - 9 = 5
2
1x - 1x + 4 = 5 - 2
0, undefined, No X
2x - 1x - 5 = 5
10
3x + 7 = 3x + 7
0, no X, undefined
2x - 5 = 3
4
x = x
Undefined, no X
x - 5 - 3 = 7
14
-12
-3x - 2 = -17
5
x - 6 + 7 = 12
11