How can you determined the sale price if you are given the regular price and the percent of markdown

What is the difference between regular convex and concave polygons

Kayla wants to find the width, ab, of a river. she walks along the edge of the river 65 ft and marks point c. then she walks 25 ft further and marks point d. she turns 90° and walks until her location, point a, and point c are collinear. she marks point e at this location, as shown. (a) can kayla conclude that δ and δ are similar? why or why not? (b) suppose de = 15 ft. what can kayla conclude about the width of the river?

What is the result of adding the system of equations? 2x+y=4 3x-y=6