ANSWER
It is the cost for printing each DVD
Step-by-step explanation
We want to find out what the slope of the equation represents.
The equation given is a linear equation. The slope of a linear equation represents the rate at which the dependent variable changes with respect to the independent variable.
The independent variable is the number of DVDs while the dependent variable is the cost to make the DVDs.
Hence, the slope represents the cost of the DVDs per DVD. In other words, it represents the cost for printing each DVD.