55 represents 100%, To find what percent represents 30, we can use the next proportion:
[tex]\frac{55}{30}=\frac{100\text{ \%}}{x\text{ \%}}[/tex]Solving for x:
[tex]\begin{gathered} 55\cdot x=30\cdot100 \\ x=\frac{3000}{55} \\ x=54.5\text{ \%} \end{gathered}[/tex]