Answer:
The function rule is:

Explanation:
Using the given input/output values, we can take two pairs of input-output values for finding the rule.
The function is a linear function as the input and output are changing linearly.
Required pairs are:
(1,-8) and (2, -11)
The general rule for linear function is:

m is the slope of the function calculated using the formula

Putting the values

Putting in equation

To find the value of b, putting (1,-8) in the equation

Putting the values

Hence,
The function rule is:
