Final answer:
To calculate the missing number of stamps (y) after 1 month (x = 1), use the linear equation y = 9 + 3x. Substituting 1 for x gives us y = 12 stamps collected after 1 month.
Step-by-step explanation:
To fill in the blank spot of the table representing the linear function for the number of stamps (y) collected after (x) months, we need to use the given linear equation, y = 9 + 3x. Since the value of y when x = 1 is missing, we will substitute x with 1 into the equation to find the corresponding y value.
y = 9 + 3(1)
y = 9 + 3
y = 12
Therefore, after 1 month, the student will have collected 12 stamps.