78
x=-3. Plug -3 into x

We will follow PEMDAS for this.
-3²=9. A negative multiplied by a negative always equals a positive.
9×2=18
18-5=13
13×6=78
PEMDAS is Parentheses Exponents Multiplication Division Addition Subtraction. You will hear of it as Please Excuse My Dear Aunt Sally to begin with.