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)
a/(-2.1)+8 = 4 // - 4
a/(-2.1)-4+8 = 0
4-0.47619048*a = 0 // - 4
-0.47619048*a = -4 // : -0.47619048
a = -4/(-0.47619048)
a = 8.39999993
a = 8.39999993
| 45/54= | | (v^2-v-12)/(32-2v^2) | | 4b+2b= | | -8.3x(-18.3)= | | -b=2 | | 7-7z=9 | | 6d+9d= | | -x+2(0)=6 | | Q+[-1]=16 | | 60+16y= | | -9x+3/-4 | | 2x^2+11x-63=0 | | m+13=15 | | 9(t-3)+3t=6(2t+5)-12 | | 4/9/2 | | -13.00+12.00x=11.00 | | 28/4/9 | | 2/21x6 | | 3=3+7y | | 118*64/236 | | 3=5+3b-13 | | 75=-15+1.5x | | 7w-9=-5 | | -x=80 | | 1.5=x+1 | | 2x^2+2y^2+16=0 | | x+7/8=9/8 | | 8=-2x-8 | | -3-(-34)+36+40-(-10)= | | 3v-2=8v | | 435=5x^3 | | x/15=10/50 |