If f(x) = 0.8(2 – x), what is the value of f(–2)?

With functions, you take the number that is in the ( ), so we have f(-2), and take the fomula f(x) = 0.8(2 – x) and everywhere you see an 'x' replace it with the -2 f(–2)=0.8(2 – (-2)) 

We will have to work with the expression of 0.8(2-(-2) When you want to evaluate these types of expressions, you want to use the Order of Operations: Parentheses, Exponents, Multiplication, Division, Addition, Subtraction. First we have to evaluate the parentheses. What is 2-(-2)
 its 4.

ok now you got 0.8 (4)

 Now we have the remains of 0.8(4). If a number is within the parenthesis, then it means that we have to multiply the number inside with the number that is outside. What is 0.8*4 its 3.2 s your answer is going to be

3.2

If you make it a little more clear i can answer it