If it's not what You are looking for type in the equation solver your own equation and let us solve it.
21=3x-18
We move all terms to the left:
21-(3x-18)=0
We get rid of parentheses
-3x+18+21=0
We add all the numbers together, and all the variables
-3x+39=0
We move all terms containing x to the left, all other terms to the right
-3x=-39
x=-39/-3
x=+13
| 3b+9=-9+b | | 9x+18=3(x-3) | | 5+2(3x-1)=4x+x+2^2 | | 2+5d=7 | | 5/2x=5/2x | | 2−8x=−8x+2 | | 4x-6+3x=6 | | 3=s+7/10 | | 15x+10=55 | | 5x+5=-4+2x+18 | | 6z-8=8z | | -9(1-4n)=63 | | 24+5x=5x+24 | | -92-x=-9x+36 | | 2(m-39)=78 | | 5x=-51 | | 6y+2+y-3=8y-8 | | -3y+10=2y+8+1 | | C=6(x+1)+3 | | -31=z/7-16 | | g=3g+8 | | 1/3(6q–2)=4q–7/3q–1/2 | | 2x(5−3)−3x=5 | | 1/2(4y+12)+3=2y+9 | | |2x|+1=9 | | 3x2+9=-27 | | 6+2.5x=41 | | -2+20-19c=-c+18 | | 3x−2=−4x−65 | | 4(z-1)^2=15 | | n(n+2)=116 | | -2(x-2)=40 |