Given the expression
[tex]3\frac{9}{12}-1\frac{11}{12}[/tex]To solve the expression above, we convert from mixed fraction to improper fraction as seen below
[tex]\frac{45}{12}-\frac{23}{12}[/tex]Then solve,
[tex]\frac{45}{12}-\frac{23}{12}=\frac{45-23}{12}=\frac{22}{12}=\frac{11}{6}=1\frac{5}{6}[/tex]Hence, the answer is
[tex]1\frac{5}{6}[/tex]