Let the missing number be x
Mean is the total sum of data over the number of data therefore,
(11+20+x+3+1) / 5 = 9
Then simplify
(35 + x) / 5 = 9
Then multiply 5 to both sides
35 + x = 45
Then subtract 35 to both sides to find x
X= 10
Hope this helps!
        
             
        
        
        
Answer: 0 = − 2, Is the answer I think. Sorry if it's wrong.
 
        
             
        
        
        
Answer:
BCDA is equivalent to FGHE
A is equivalent to angle E
B is equivalent to angle F
C is equivalent to angle G
D is equivalent to angle H
Step-by-step explanation:
1st step is just figuring out which sides corresponds with which.
A is equivalent to angle E
B is equivalent to angle F
C is equivalent to angle G
D is equivalent to angle H
On the last one I am confused by what it is asking, but here is what I think: 
The scale factor from the big figure to the small figure is 1.5 because of 15/10=1.5
12/8=1.5 and so on.