Consider the function y = f (x), the element 'x' is the input of the function, and 'y' is the value of the function or the output.
Now, we have to determine the equation for " Nine times the input minus seven is equal to the output"
Since, the input of the function refers to the variable 'x' and output of the function refers to the variable 'y'.
The required equation is:
[tex]( 9 \times x)-7 = y[/tex]
So, [tex]9x-7 = y[/tex]
Therefore, 9x-7=y is the required equation.
Therefore, Option C is the correct answer.
