Since this expression has no equal sign, the only thing you can do is to reduce it.  Do this with the "order of operations"
.
8x +3 { 2 -6 (2x -3)} 
First, distribute the -6 to terms inside the parenthesis:
8x +3 { 2 - 12x + 18} 
Next, distribute the 3 to terms inside the braces:
8x + { 6 - 36x + 54} 
Next, remove braces:
8x + 6 - 36x + 54 
Group terms:
(6+54) + (8x - 36x)
60 - 28x
You could leave the answer the way it is above, or you could factor as:
4(15 - 7x)