If it's not what You are looking for type in the equation solver your own equation and let us solve it.
f in (-oo:+oo)
-12 = f/(-3) // - f/(-3)
-(f/(-3))-12 = 0
1/3*f-12 = 0 // + 12
1/3*f = 12 // : 1/3
f = 12/1/3
f = 36
f = 36
| 3(x-4)-4x=2-8 | | -8=y/-2 | | 2y-2=2x | | 3.14*1+x=23 | | 5/3+2/3x=25/12+7/4x+1/6 | | .58y+-.25=2y+-1.66 | | V/-14=-7 | | 6=r/-12 | | -7=p/-9 | | -3h=-27 | | -4s=-24 | | 9x+7=3x-11 | | -8k=32 | | .75b-.20b=11 | | -91=13c | | -57=19b | | 88=-11m | | 64=2x | | 13v=39 | | 1-2sin^2x+cosx=0 | | -3a=51 | | 1x+0.5x=x | | -9h=-81 | | 0.9(4x+8)=1.7-(x+2) | | 7x+2=3(x-4) | | 6g=-36 | | (6/500)x=600 | | 3xy^2-5yz=4x | | -3p=6p | | 4y-6+y+17=5y+20-3y | | 28=7m | | 4m/3-m/6=72 |