describe how you can tell by lookin at a graph of a function which variable is the input variable and which is the output variable

The output variable will be on the y-axis, the input variable will be on the x-axis.

Step-by-step explanation:

To create a function, we must an equation in the form of

The x-axis of a graph will be what we change in the function. We will get a certain value () that changes when the right side of the function changes. This means that the input of the function will be .

The y-axis of a graph will be what the x-axis makes. In this case, it's . This is the output of the graph after given the input.  This means the output is .

Hope this helped!