"Hope this is your question, if not I think you will, still be able to find an answer of your question based on this solution"
The expression is :
2(z-4)
so we may think that the given value is z = 12.8 instead of x=12.8, then only we can plug it in given expression.
so plugging z=12.8 in the expression:
2(12.8-4)
We will use PEMDAS rule here,
So simplifying parenthesis first,
12.8-4 = 8.8
Now multiplying the result 8.8 with 2 to get the answer,
8.8 *2 = 17.6
Answer : 2(z-4) = 17.6 for z=12.8
"hope this helps"
