Answer
See below.
Work Step by Step
The difference between subsequent terms is constant, hence it is an arithmetic sequence with $a_1=1.6$ and common difference $1.6$. Thus the next term is $8$.
The nth term of an arithmetic sequence can be obtained by the following formula: $a_n=a_1+(n-1)d$, where $a_1$ is the first term and $d$ is the common difference.
Hence here $a_n=1.6+(n-1)1.6=1.6n$.
