Let the directions are defined by vectors as following
East = + x direction
West = - x direction
North = + y direction
South = - y direction
upwards = + z direction
downwards = - z direction
So here we are given that it moves
1). 10 m East
2). 9 m South
3). 3 m North
4). 2 m down
So we can write it as
[tex]d_1 = 10 \hat i[/tex]
[tex]d_2 = 9 (-\hat j)[/tex]
[tex]d_3 = 3 \hat j[/tex]
[tex]d_4 = 2 (-\hat k)[/tex]
Now total displacement will be given as
[tex]d = d_1 + d_2 + d_3 +d_4[/tex]
[tex]d = 10 \hat i - 9 \hat j + 3 \hat j - 2 \hat k[/tex]
[tex]d = 10 \hat i - 6 \hat j - 2 \hat k[/tex]
now the magnitude of the displacement will be
[tex]d = \sqrt{10^2 + 6^2 + 2^2}[/tex]
[tex]d = 11.8 m[/tex]
so the magnitude of displacement will be 11.8 m