Which of the following arguments correctly justifies the second step of the flow proof of the triangle angle sum theorem below?

A.
Linear pair postulate
B.
Vertical angles theorem
C.
Alternate exterior angles theorem
D.
Alternate interior angles theorem

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?

Δabc is reflected across line l to form δ alblcl, and a¯¯¯al¯¯¯¯ intersects line l at point d. which equation is not necessarily true?

How do you find the circumfrance of a circle?