The dependent variable is the pages per minute. Its kind of confusing but I'll try to make sense.
Say you have a job. You are working for $10 per hour. If you work more hours, you make more money. So the independent variable, which can be controlled by you, is the hours, or in your equation, the minutes. The dependent variable, which is controlled by the independent variable, so the dependent variable is the money, or in your equation, the pages printed.
You can control the independent variable, which then controls and changes the dependent variable. If it makes sense.
To answer your question, the dependent variable is the pages printed, and the independent variable is the minutes.
