1) Let's check which one has the sum or difference:
[tex]\begin{gathered} B)\frac{11}{12}-\frac{1}{6}=\frac{11-2}{12}_{}=\frac{9}{12}=\frac{3}{4} \\ C)\frac{3}{5}+\frac{3}{20}=\frac{12+3}{20}=\frac{15}{20}=\frac{3}{4} \\ E)\frac{2}{3}+\frac{1}{12}=\frac{8+1}{12}=\frac{9}{12}=\frac{3}{4} \end{gathered}[/tex]Note that we need to find a common denominator for those.
2) Therefore, the answer is
[tex]B,C,E[/tex]