What you would do is divide all of the minutes by the amount of pages to find how long for each rate for one page. (ex. 18/12, Michael reads 1 page in 1.5 minutes. 12/8, Michael reads 1 page in 1.5 minutes. 30/20, Michael reads one page in 1.5 minutes) Therefore, yes it is proportional, and the equation is y=1.5x (there is no y intercept)
