If it's not what You are looking for type in the equation solver your own equation and let us solve it.
21=3b
We move all terms to the left:
21-(3b)=0
We move all terms containing b to the left, all other terms to the right
-3b=-21
b=-21/-3
b=+7
| 13+6+2x-18=4x-24 | | -5x-1+3x=-15 | | 2x+2x*12=4 | | -5r+2=42 | | 2=b+8-7 | | 3/4(12x+24)-5=-2/3(6x-24) | | 4(x-6)-6(x-4)=x+7-(x-7) | | 21–x=13 | | -8+f/6=10 | | 16x-(9x-2)=9 | | u/2+5=-37 | | 16x-|9x-2|=9 | | r/3-4=17 | | 2c+7.5=-3c+6.2 | | 11h+15=136 | | 1/2x+2/3=19/20 | | -7-6n=41 | | 28-2(2w+1)=(w-2(9+w) | | 5h-1=19 | | 14=x/16 | | 5+11m=13m | | x/11=-4 | | -26.2+m=-44.4 | | (-10+5x)+40+90=180 | | x+2x+2x+12=992 | | 2x^2+155=-45 | | 9m-3(m+6=2(m+1) | | 2/3x-156=39/24 | | x+1/5=-3/4 | | 13+6+2x-18=29 | | -9t=10−4t | | 6x-18=2x+7 |