We can convert improper fractions to mixed numbers through long division. So, #11/3# can also be seen as 11 divided by 3.
Setting up the division:
#color(white)(xxxxx)3 color(white)(x)2/3 color(white)(xxxxxxxx)#
# color(white)(xx) 3| bar(11color(white)(x)) color(white)(x) color(white)(x)
color(white)(x) color(white)(x) color(white)(xxx)#
#color(white)(xxxx)ul(color(white)(x)9)color(white)(darr#
#color(white)(xxxxx)2 color(white)(x)#
Because three goes into eleven #3# whole times and we get a remainder of #2# ("leftover" is #2/3#) :
#11/3 = 3 2/3#