Calculate the rise and run to find the slope of each line.

Step 1 ：The slope of a line is calculated by the formula \(\frac{y2 - y1}{x2 - x1}\), where \((x1, y1)\) and \((x2, y2)\) are two points on the line.

Step 2 ：To find the slope, we need to know two points on the line. However, the question does not provide any specific lines or points.

Step 3 ：Therefore, we will create a function that takes two points as input and returns the slope of the line passing through these points.

Step 4 ：The function should work correctly for calculating the slope of a line given two points.

Step 5 ：The function will return 'undefined' if the line is vertical (i.e., the x-coordinates of the two points are the same), as the slope of a vertical line is undefined.

Step 6 ：Final Answer: \(\boxed{\text{The final answer is a function that calculates the slope of a line given two points. The slope is calculated as } \frac{y2 - y1}{x2 - x1}, \text{ and the function returns 'undefined' if the line is vertical.}}\)