Im a keep editing since this is timed. 
#1 x-8a/6=3a-2x
Multiply each term by 6 to remove fraction .
6(x-8a/6)= 3a(6)-2x(6)
X-8a=18a-12x
Add 12x both sides 
X+12x-8a=18a-12x+12x
13x-8a= 18a
Add8a both sides 
13x-8a+8a=18a+8a
13x=26a
Divide each side by 13
13x/13=26a/13
X= 26a/13
Reduce and cancel common factor .
X= 13(2a)/13(1)
X=2a/1
X=2a
Problem #2
3x-2a=7a find a 
Subtract 3x both sides 
3x-3x-2a=7a-3x
-2a=7a-3x
Subtract 7a both sides 
-2a-7a=7a-7a-3x
5a=-3x
 
Divide both sides by 5
5a/5=-3x/5
A= -0.6 or -3/5 
Problem#3
3(bx-2ab)=b(x-7a)+3ab
Distributed property
3(bx)+3(-2ab)=b(x)+b(-7a)+3ab
Simplify
3bx-6ab=bx-7ab+3ab 
Add -7a plus 3ab on right side 
3bx-6ab= bx-4ab 
Subtract bx both sides
3bx-bx-6ab= bx -bx -4ab
Simplify 
2bx-6ab= -4ab
Add 6ab both sides
2bx-6ab+6ab=6ab-4ab
2bx=2ab
Divide 2b both sides
X= 2ab/2b 
Cancel 2 common 
X= ab/b 
X=a