first you need to simplify it so
5 7/8 = 5x8=40 40+7=47 so at the moment you have 47/8
then do
11/4 is fine so find the common denominator
in this case its 8 so 4x2=8 and then 11x2=22 so you have 47/8-22/8
which = 25/8 then you simplify and you get 3 1/8