4equal side,2 opposite side parallel, no right angle

Rachel reads 1/5 of the pages of a book plus 12 pages on the first day. on the second day, she reads 1/4 of the remaining pages plus 15 pages. on the third day, she reads 1/3 of the remaining pages plus 18 pages. on the fourth day, she reads the remaining 70 pages. how many total pages are in the book?

Anyone know? is appreciated! will mark brainliest if correct!

In a graph with several intervals o data how does a constant interval appear? what type of scenario produces a constant interval?