If the Math Olympiad Club consists of 15 students, how many different teams of 3 students can be formed for competitions?

Fractions can be added and subtracted only if they're fractions. a. like b. proper c. improper d. unlike

Can someone answer this question? : )

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?