Find the surface area of the rectangular prism

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?

I'll give brainliest if you answer right : )

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5