An arithmetic sequence is a sequence where the next term is obtained by adding a fixed amount to the current term. This can be written mathematically:
[tex]a_{n+1}=a_n+d[/tex]Since the current term is 56, this means that the next term is:
[tex]\begin{gathered} a_{n+1}=56+72 \\ a_{n+1}=128 \end{gathered}[/tex]