Word problem- Kenji packed an exercise ball into a cylinder package. How much spices does the package occupy in terms of pie/3.14

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?

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)