If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( x )
12-x = 0
12-x = 0
12-x = 0
12-x = 0 // - 12
-x = -12 // * -1
x = 12
x in (-oo:12) U (12:+oo)
6 = (4*x)/(12-x) // - (4*x)/(12-x)
6-((4*x)/(12-x)) = 0
6-4*x*(12-x)^-1 = 0
(-4*x)/(12-x)+6 = 0
(-4*x)/(12-x)+(6*(12-x))/(12-x) = 0
6*(12-x)-4*x = 0
72-10*x = 0
(72-10*x)/(12-x) = 0
(72-10*x)/(12-x) = 0 // * 12-x
72-10*x = 0
72-10*x = 0 // - 72
-10*x = -72 // : -10
x = -72/(-10)
x = 36/5
x = 36/5
| X-2(-.3)=2 | | 13=5x+11 | | 3n+2=3 | | 3(2+2y)+4y=3 | | 7+4q=11+34 | | 6+6x=6(x-5) | | 7(x+4)=-2(5x-5)+2x | | (2x+1)-(-4x-9)= | | x+3x+6x=3450 | | 12(10)+3(14)=162 | | 9-x=x+12 | | 7-2n=4 | | 8(10)+3(14)=122 | | 4z-5=8x+3 | | -3(-2w+3)-9w=3(w-7)-3 | | 2y(y)=400 | | 2.1x-12.2= | | 481.194=13.4*6.3*w | | 3x-4+2x+10=21 | | -12/5=-6u | | -3(2x-4)=5x | | 3x+7-9+x=2x+3-x+4 | | -21=7/8y | | -6=-3/5w | | X+Y-3Z= | | (x^5)^(9/5) | | 5/2v=15 | | 4(b-3)-6=2(b+5) | | 7-4(x-4)=2*x | | -2x+4.25=-2x-8.75 | | e-2=17 | | .5x+18=4 |