Final answer:
The student's question involves evaluating the expression 28/z - z/4 + 9 for z=4. After substitution and simplification, the final answer to the expression is 15.
Step-by-step explanation:
The student is asking for the evaluation of an expression with a given variable value.
The expression is 28/z - z/4 + 9, and the value given for z is 4. To solve this, we substitute z with 4 and perform the calculations.
First, we calculate 28 divided by 4, which is 7. Then we calculate 4 divided by 4, which gives us 1.
So, the expression becomes 7 - 1 + 9.
Adding and subtracting in order from left to right, we get 6 + 9, which equals 15.
The final answer to the expression 28/z - z/4 + 9 when z is 4 is 15.