Hi Conor,

These are special sequences called arithmetic sequence. The property that makes them arithmetic sequences is that the difference between any two successive terms is the same amount. Look at your first sequence

3.5, 5, 6.5, 8, 9.5, ...

The difference between any two successive terms is 1.5.

The first term is 3.5.
The second term is 3.5 plus 1.5.
The third term is 3.5 plus 1.5 twice.
The fourth term is 3.5 plus 1.5 three times.
The fifth term is 3.5 plus 1.5 four times.

So, what's the nth term?
Penny