If it's not what You are looking for type in the equation solver your own equation and let us solve it.
a in (-oo:+oo)
-4*a = -12 // + 12
12-4*a = 0
12-4*a = 0 // - 12
-4*a = -12 // : -4
a = -12/(-4)
a = 3
a = 3
| k+2=-9 | | -10+t=-1 | | b+9=6 | | b+7=13 | | 16=t+10 | | -1=k-6 | | w/7=6 | | b/6=-3 | | t+8=10 | | 16=b+7 | | w+4=7 | | -9+d=-3 | | -2+m=-2 | | d/-4=-5 | | 8/7x=104 | | 7w=21 | | -8+m=-2 | | 16=a+7 | | 4+d=16 | | -8+a=-1 | | (2x+5)(2x+5)=-7 | | -3d=-9 | | a-7=-12 | | -5+t=-12 | | 10=k+10 | | 2/3*3/2(x+9)= | | m+7=15 | | 7=d+10 | | 116-3x=5x+12 | | -5=m+7 | | d+4=8 | | -5k=15 |