Answer: 28
Step-by-step explanation:
The mean of 15 numbers = 12
Then , the sum of the numbers = 12x15 = 180
Let the extra number included be
, then
The new sum = 
And the new total number will increase from 15 to 16
new mean = 13 , so we have :





therefore , the extra number is 28
Answer:
I'm pretty sure its D if not I'm sry
7/3=L/9
⇒63=3L
⇒L=21
which mean the Length equal 21 tiles and width equal 9 tiles for the new rectangle.
18 + -8
Don't forget to always put the number with the greatest absolute value first! And mark as brainliest!