How do you calculate displacement and direction in spelunking cave explorations?

[jamiebean]

Homework Statement

attached below:

Relevant Equations

resultant displacement=√x^2-y^2

in part a, i tried to draw the scale and tried to determine the magnitude. But I still don't get why is the answer written in that way.
in part b: i know that x180/pi calculates the degree, but i don't understand how does this calculates the direction.
and i don't understand what's happening in the brackets.

 

[haruspex]

why is the answer written in that way.

For each movement, work out what the EW displacement is and what the NS displacement is.
Add up the EW displacements, making W negative and E positive (say).
Do the same for the NS displacements, N positive.