Let's analyze the pattern in the table:

Observing the y-values:

• 9 → 12 (increase by 3)
• 12 → 15 (increase by 3)
• 15 → 18 (increase by 3)

Since this follows a linear pattern, the next value should be: $18 + 3 = 21$

Thus, the missing value in the table is 21.

Would you like a further breakdown of the solution?

Related Questions:

1. How can you determine if a sequence follows a linear pattern?
2. What is the general formula for a linear sequence?
3. How can you find a missing value in an arithmetic sequence?
4. How do you calculate the common difference in a linear pattern?
5. Can you derive a formula to find any term in this sequence?

Tip:

For a linear sequence, the general formula is: $y = mx + b$ where $m$ is the common difference, and $b$ is the y-intercept.