Answer :

TSO
So to solve your question, we can use this: 

[tex]\sf{a(b-c) = ab-ac}[/tex]
[tex]\sf{a(b+c) = ab+ac}[/tex]

So then 

[tex]\sf{-(6w-1)}[/tex]

If we use the above formulas then:
[tex]\sf{-(6w-1) = -6w+1}[/tex]

And for
[tex]\sf{3(w-4)}[/tex]

We will get:

[tex]\sf{3(w-4) = 3w-3(4) =3w-12}[/tex]

And to simplify
[tex]\sf{-(6w-1)+3(w-4)}[/tex]

Since we already calculated the individual parts, not put them together, so:

[tex]\sf{-6w+1+3w-12}[/tex]

Now we have to add the like terms which are -6w and 3w. And also 1 and -12.

Rearranging the terms, we get:

[tex]\sf{-6w+3w-12+1}[/tex]

And [tex]\sf{-12+1=-11}[/tex]

And also [tex]\sf{-6w+3w= w(-6+3) = w(-3) = -3w}[/tex]

So combining that, we get:

[tex]\sf{-3w-11}[/tex]

Which is your final answer :)