Determine the number of classes in the frequency table below.
[tex]\begin{tabular}{ll}
\hline Cass Frequency \\
\hline [tex]42-43[/tex] & 7 \\
[tex]44-45[/tex] & 2 \\
[tex]46-7[/tex] & 6 \\
[tex]45-49[/tex] & 4 \\
[tex]40-51[/tex] & 1 \\
\hline
\end{tabular}[/tex]

5
2
6
20