I'm assuming you mean

Write the 2 as a fraction 2/1 and multiply.
 
 
        
        
        
Answer:
80cm^2
Step-by-step explanation:
20*5=100
10*2=20
100-20=80
 
        
             
        
        
        
Answer:
25
Step-by-step explanation:
Let n be the first integer. 
Then the second integer will be (n + 1). 
And the third will be (n + 2). 
The sum is 78. Therefore: 

Solve for n. Combine like terms: 

So: 

Therefore: 

Therefore, the first integer is 25. 
So our sequene is 25, 26, and 27. 
The integer closest to zero will thus be 25. 
 
        
                    
             
        
        
        
Answer: Irrational
Step-by-step explanation:
It is irrational because you cannot multiply a number by the same number to get the square root of 2.
I think the approximation is 1.4 or 1.42
 
        
             
        
        
        
20*1.95 =39 girls
26girls/39girls =0.667
0.667*100 = 66.67%