When trying to find the cumulative distribution function when dealing with fractions, why is the denominator not integrated?

Part a: solve –mk – 120 > 95 for m. show your work. (4 points) part b: solve 2c – 9f = 45 for f. show your work. (6 points)

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?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?