2 people working at the same rate will take 9 hours to paint a room assuming that they all work at this rate how long will it take 3 people to paint the room

Whats the name of the vertical axis

In the diagram, points d and e are marked by drawing arcs of equal size centered at b such that the arcs intersect ba and bc. then, intersecting arcs of equal size are drawn centered at points d and e. point p is located at the intersection of these arcs. based on this construction, m , and m

Can someone explain to me how to do