here our distance is given with respect to ticket booth
initial distance is given 50 m from the booth
So our initial position is
[tex]x_i = 50 m[/tex]
now after this finally we reach at final position
[tex]x_f = 5 m[/tex]
now change in position is given as
[tex]\Delta x = x_f - x_i[/tex]
[tex]\Delta x = 5 - 50 = - 45 m[/tex]
so change in position is 45 m in magnitude and since we are coming closer to the booth so its coming negative in sign