To start, the first thing you need to do is to find the slope of your x and y values, or in other words, your rate of change. To do this, use the slope intercept formula or (y2-y1)/(x2-x1) and you can use any two pairs of x and y values.
Using the x and y values of (2, 96) and (3, 76.80), plug the values into the slope intercept formula. This would look like this:
(76.80-96)/(3-2)
When you simplify, you should get -19.2/1 or simply -19.2 as your slope.
Then, using the linear equation y=mx+b, plug in a coordinate point into the x and y variables and plug your slope into the m value in order to solve for the value of your y-intercept, or b.
This would look like this:
96=-19.2(2)+b
When you simplify, you will get 96=-38.4+b and when you solve for b, you get that b=134.4
Now that you have your slope and your y-intercept, you can conclude that the equation to this input/output chart would be
y=-19.2x+134.4