Evaluating Algebraic Expressions with Substitution

 $Evaluate\ 4-x\ when\ x=2$  

 $Evaluate\ 4-x\ when\ x\ =\ -2$  

 $Evaluate\ -4-x\ when\ x=-2$  

 $Evaluate\ -4\ +x\ when\ x\ =\ -2$  

 $Evaluate\ \left(x+17\right)+\left(y-17\right)\ when\ x\ =\ -4\ and\ y\ =\ 4$