Michael reads 12 pages of a book in 18 minutes, 8 pages in 12 minutes, and 20 pages in 30 minutes. Is this a proportional relationship?

If the child reads 12 pages in 18 minutes, that is 12/18 pages/minute, 12/18 can be reduced to 2/3 pages/minute by dividing top & bottom by 6. The rate is 2/3 page / minute (let that sink in: for every ONE minute, the child reads 2/3rd's of a page). Now given 30 minutes, the child can read 2/3 pages/minute * 30 minutes = 20 pages.