(12-8)(7-4)3power

I think you mean

(12-8)(7-4)^3

Just checking, because an extra bracket around like ((12-8)(7-4))^3 would give a different answer.

Brackets first.
Then powers or roots.
Then multiply or divide.
Then add or subtract.

First do the arithmetic inside the brackets:

(4)(3)^3

Now evaluate the power. What is 3^3? That's 3*3*3. Now multiply that snswer by 4, and you're done.