Answer:
The table shows a relation where the first is sum by other number to obtain the second colum.
So, 1 + 0 = 1, the first row.
2 + 1 = 3
3 + 2 = 5
As you can see, the increasing number is the added part, and increases by one, that's the rule.
Then,
4 + 3 = 7
15 + 4 = 19
Therefore, the complete table is
1 1
2 3
3 5
4 7
15 19
