Solving those simple linear equations, by isolating the variable, and combining like terms.
1.3x-4=23
3x -4=23
3x=27
x=9
2) 9-4x=17
-4x =17-9
-4x=8
4x=-8
x=-2
3) 6(x-7)=36 Distributing the factor
6x -42=36
6x=36+42
6x=78
x=13
4) 2(x-5)-8=34 Distributing the factor
2x -10-8=34
2x -18=34
2x=52
x=26