Answer:
40000
Step-by-step explanation:
4×10^4 = 4×10000 = 40000
 
        
                    
             
        
        
        
Answer:57+51+3
Step-by-step explanation: use https://www.cymath.com/
 
        
             
        
        
        
3:5=x:50
Therefore 5 ×x = 50 
x = 10
Therefore 3 × 10 = 30
therefore 30 blue pens 
proof = 30 blue + 50 red= 3+ 5
 therefore 80 = 8x
        
                    
             
        
        
        
We know that the perimeter of a cylinder is 2πr we will find it as we do always. The perimeter will be :
2 pi r 
= 2 pi * 20
= 40 pi 
Because it says rounded to the nearest tenth the answer will be : 125.6 cm^3 
Because we have a half of a cylinder we will just divide the answer we got by 2:
125.6cm^3 /2 =62.8
The answer is 62.8 cm^3