Help!!

6(a+3)=18 + 6a

6a + 18 =  18 + 6a

Since one side equals the other, we have infinite solutions for  "a" 

1/5(25−5a) = 4−a

5 - a  =  4 - a       add a to both sides

5  = 4

This is an absurd solution.....thus.....there are no solutions for "a"

9x =  5x+20      subtract 5x from both sides

4x  = 20            divide both sides by 4

x  = 5

I assume this is :

[6x−2] / 4 = x−2     multiply both sides by 4

6x - 2  = 4 (x - 2)

6x - 2  = 4x  - 8      add 2 to both sides, subtract 4x from both sides

 2x  = -6               divide both sides by 2

x  = -3

8/9(54x−36)+2=−3/4(−40+16x)+90x

48x - 32 + 2   =  30  -  12x  + 90x

48x - 30  =  30 + 78x           add 30 to both sides, subtract 78x from both sides

-30x  = 60          divide both sides by -30

x  = -2