Given the following input-output pairs, find the relationship between x and y, complete the table, and describe the relationship in words, a number sentence, and a flow diagram.

Observe the given pairs from the table: $(1, 5)$, $(2, 7)$, $(3, 9)$.
The difference between consecutive output values is constant: $7 - 5 = 2$ and $9 - 7 = 2$. This indicates a linear relationship of the form $y = mx + c$.
The slope $m = 2$.
Substitute a point, for example, $(1, 5)$, into $y = 2x + c$:

The relationship between the input and output is $y = 2x + 3$.

Using the relationship $y = 2x + 3$:
For $x = 4$: $y = 2(4) + 3 = 8 + 3 = 11$
For $x = 5$: $y = 2(5) + 3 = 10 + 3 = 13$
For $x = 6$: $y = 2(6) + 3 = 12 + 3 = 15$

The completed table is:

The output is found by multiplying the input by 2 and then adding 3.

Input (x) $\rightarrow$ Multiply by 2 $\rightarrow$ Add 3 $\rightarrow$ Output (y)