The opposite interior angles in a rhombus must be equivalent,
therefore:
[tex]\begin{gathered} m\angle ABC=3m\angle BAD \\ where \\ m\angle ABC=m\angle ADC \\ m\angle BAD=m\angle DCB \\ so\colon \\ 3m\angle BAD+3m\angle BAD+m\angle BAD+m\angle BAD=180 \\ 8m\angle BAD=180 \\ m\angle BAD=\frac{180}{8} \\ m\angle BAD=22.5 \end{gathered}[/tex]Hence:
[tex]m\angle ABC=3m\angle BAD=67.5[/tex][tex]\begin{gathered} m\angle EBC=\frac{m\angle ABC}{2} \\ m\angle EBC=\frac{67.5}{2} \\ m\angle EBC=33.75 \end{gathered}[/tex]
