Does the unit rate always have to be set up as the denominator?

What is the smallest integer n such that n\sqrt{2} is greater than 20

Somone me i want to know what 18 hours out of 24 hours in a fraction

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?