I don't know how to do this I need help

Plz me plz i will give a brain just plz

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?

Part a : solve - vp + 40 < 65 for v . part b : solve 7w - 3r = 15 for r show your work!