From the grouped frequency table a) What is the class centre in the first row? b) The sum of the frequencies is?

\[\begin{array}{ | c | c | c| } \hline \quad \text{Class} \quad & \quad \text{Class Centre} \quad & \quad \text{Frequency } \quad \\ \hline 5-14& &9\\ \hline 15-24 & &17\\ \hline 25-34& &16\\ \hline 35-39& &8\\ \hline & \text{Total}& \\ \hline \end{array}\]