Sara claims that the number of pages she has read in her book is proportional to the number of minutes that she has spent reading. She collects several data points to prove her claim and expresses the data points as (x, y) coordinate pairs.
Some possible data points that Sara could collect to prove her claim are:
(10, 30) - She has read 10 pages in 30 minutes.
(20, 60) - She has read 20 pages in 60 minutes.
(30, 90) - She has read 30 pages in 90 minutes.
(40, 120) - She has read 40 pages in 120 minutes.
To prove her claim, Sara would need to show that the ratio of pages read to minutes spent reading is consistent across all data points. In this case, the ratio is always 1:3.