Answer:
9.8 Inch
Step-by-step explanation:
The distance from the upper left corner to the bottom right corner of the box is the longest diagonal of the box.
For a rectangular prism:
Length of the Longest diagonal 
Therefore:
Length of the pencil

 
        
                    
             
        
        
        
|12| ÷ 2 • |-5|
= 12 ÷ 2 • 5
= 6 • 5
= 30
Absolute values just make the number positive if it is negative. The number stays positive if it’s positive.
        
             
        
        
        
Pic 1 is correct
Pic 2 is correct
Pic 3 is correct