These are called integer numbers.
We start with natural numbers (or whole numbers), i.e. the set

When you add the opposite of each whole number, you have the set of integers:

 
        
                    
             
        
        
        
 Volume of water in the glass = 3 x 2 x 4 = 24 cubic cm.
Volume of water plus the ring = 3 x 2 x 4.25 = 25.5 cubic cm.
Subtract the total with the ring from just the water:
25.5 - 24 = 1.5 cubic cm
 
        
             
        
        
        
Answer:
21.64
Step-by-step explanation:
7.7+0.94+13=21.64