I tried to show all work.
 
        
        
        
Answer:
1 inch
Step-by-step explanation:
The perimeter is the sum of the lengths of the sides:
Perimeter = 3/23 + 9/23 + 11/23 = (3 + 9 + 11)/23 = 23/23 = 1
 
        
             
        
        
        
Answer:
Because we actually divide by 10 when a number is multiplied by 0.1.
Step-by-step explanation:
Let  be a number.
 be a number.
When we multiply a number by 10:
 (One '0' is increased in the number)
 (One '0' is increased in the number)
For example:

Considering a decimal number:

Multiplying a number with 0.1 (which is actually  ) means dividing the number by 10.
) means dividing the number by 10.

Considering a decimal number:

<em>Therefore, When multiplying a number by 0.1, move the decimal to the left.</em>
 
        
                    
             
        
        
        
There are a total of 900 students at Molly’s school. 810 is 90% of 900. 90% of students did not wear a silly hat.
        
             
        
        
        
Answer:
495 in
Step-by-step explanation:
The formula for the volume of a triangular prism is V =  · w · h · l, where w represents with, l represents length, and h represents height. Using this and plugging in the values, we can solve.
 · w · h · l, where w represents with, l represents length, and h represents height. Using this and plugging in the values, we can solve.
V =  · 5 · 11 · 18
 · 5 · 11 · 18
V = 2.5 · 11 · 18
V = 27.5 · 18
V = 495
hope this helps :)