Two lines have equations y + m1x + c1 and y + m2x +c2, m1m2 = -1. prove that the lines are perpendicular.

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?

The water has been on the stove y=9.5x+62.1 after how many minutes will the tempature be 138.1 f

What are the solutions of the system? solve by graphing. y = x^2 + 3x + 2 y = 2x + 2