You would use PEMDAS
P stands for parentheses, x-5 can’t be simplified, so on to E.
E stands for exponent so next you would square x-5 getting x^2-10x+25.
M stands for multiplication, you multiply your result from E by -2. So, -2(x^2-10x+25)+8. And then -2x^2+20x-50+8.
D stands for division, and there is none so moving on.
A stands for addition, and so we add next. -2x^2+20x-42.
You can’t simplify any further so there you go!
Hope this helps!