I'd say the correct answer is D bc it's talking about the SAS theorem, excuse me if I'm wrong tho.
Answer:
The missing number on the given data set is 12.
Step-by-step explanation:
Here, the set of data = 18,16_,9,12,23
Let us assume the missing number in the data = m
The mean of the data = 15
Total number of observations = 6
Now, Sum of the data = 18 + 16 + m + 9+ 12+ 23 = 78 + m
Also, 

or, m = 12
Hence, the missing number on the given data set is 12.
4y.
Is the answer
Hope this helps
Answer:
a
Step-by-step explanation: