which equation is point slope form represents a line with m equals -1/2 that goes through the origin

What is the point slope form of a line with slope -5 that contains point (2,-1)

Ineed with the quizzes in apex mathematics ii

The stairs leading from the ground to the entrance of a plane forms a right triangle with the ground. if the distance of the stairs measures 22 feet and the ground distance measures 11 feet, how high is the entrance to the plane from the ground? which diagram represents this scenario? / 22ft © 22ft 11 ft 11 ft 22 it