In the triangle below which is equivalent to sin a 30 60 90 triangle abc

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?

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

Need on this geometry question. explain how you did it.