If it's not what You are looking for type in the equation solver your own equation and let us solve it.
20a=420
We move all terms to the left:
20a-(420)=0
We move all terms containing a to the left, all other terms to the right
20a=420
a=420/20
a=21
| 36=6^2x-1 | | 2y+9÷3=3y+10 | | 36=(6^2x-1) | | 16=x-1/3 | | 3x251=1123 | | 6n=(-48) | | 2513x=1123 | | 3x+15=3x+8 | | 4x=8x+4 | | 4x-(7×+2)=4-3x | | 3÷i=46+i | | -1/2(4a+8)=-2a=4 | | 7x+23x-7=6(5x+8) | | 3/6t+4/6=2/6-t | | 14y+8y=24 | | 4x+12x-7=4(4x+1) | | 2x+3+7x= | | -1/2(4a+8=-2a+4 | | 2(2x)+3=6x+4 | | 6a^2+12a+2=0 | | 15x^2+45x-9=0 | | k(k+2)=168 | | 8.9x+77.98=-11.1x+77.48 | | p2-4p+18=0 | | 4(6z-1)-2(z+6)=7(z+1) | | 5x–3=x+17 | | -9(t-4)-(t+8)=6 | | X^3=6x+20 | | 3(x+6)+2(x+3)=64 | | 3x+6=-4x+6 | | 5p=20+21 | | (3x+5)^2=-1 |