How do you do this? Choices are 23 24 31 and 36

Nikolas calculated the volume of the prism. his work is shown below.

The bottom of ignacio's desktop is 74.5cm from the floor. ignacios sits in his adjustable chair, and the tops of his legs are 49.3cm from the floor. each clockwise rotation of the knob on the chair raises ignacio's legs by 4.8cm. write an inequality to determine the number of clockwise rotations, r, ignacio could make with the knob without his legs touching the desk.

What is the angle measure, or angle of depression, between this bird and the bird watcher?