Harry buys 3 packs of ruled notepads. each pack has same number of notepads. stella buys 4 packs of plain notepads. each pack has same number of notepads. if a represents the number of ruled notepads and b represents the number of plain notepads, write the expression showing the total number of notepads.

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?