A. x=0, as you need to subtract five from both sides for you to have only the x on the left side and the value of x on the right side.
B. 2x-6=(3x-x)+(1-7)
2x-6=2x-6
0=0
therefore, all real numbers are accepted values of x.
C. 3x+1=43
3x=42
x=14
D. 4x-1=4x+7
4x=4x+8
0=8, which is wrong
therefore, there are no accepted value of x.