If it's not what You are looking for type in the equation solver your own equation and let us solve it.
21-3m=12
We move all terms to the left:
21-3m-(12)=0
We add all the numbers together, and all the variables
-3m+9=0
We move all terms containing m to the left, all other terms to the right
-3m=-9
m=-9/-3
m=+3
| 4b+5b=-6b-15 | | 79=31+3v | | 9x2+12x=32 | | 13w+16w-7+6=-5w+6-7 | | 14+6x=5x+3x | | 6×(x+0.05)+4x=4.80 | | 3/2x+4/3=5/8x+5/2 | | 108=-4(1-7x) | | 16−2c=12 | | x+2x+7=65 | | 3/s-1=3 | | 402=-6(8a-3) | | 5(-5y+3)=15 | | t/2+9=13 | | 21=-3v-4v | | t2+ 9= 13 | | 19=1+3r | | 2(-8x+5)-13=9(-x+1)-112 | | 15/6z=22 | | 137x125=17,125 | | X^+2x-33=0 | | 18+t=50 | | 6.45=x/(0.3-x)/(0.4-x) | | 17(9c-1)-16=151c+17 | | 1/4(x+40)=1/2(x+20) | | (1/4)=(81/x) | | K/3+5k=-2k | | 1/2x+4=2x-0.5 | | 892x-14)+13=4x-27 | | 60.52=11.4x+0.1 | | 5x+15=5x-1 | | 6x+5(-13+x)=7 |