Answer:
160 inches
Step-by-step explanation:
An octagon has 8 sides;
20*8=160
 
        
             
        
        
        
Answer:
3446.464 m³
Step-by-step explanation:
280 cm=2.8 m
S=πr²×h×14
   =3.14×2.8²×10×14
   =3446.464 m³
 
        
             
        
        
        
Answer:
Gina is 12 years old
Step-by-step explanation:
First,  we will have to write these statements mathematically and then solve.
Let Gina's age be x, let Gina's brother's age be y and let Gina's sister's age be z.
The second statement"Gina's older sister is twice Gina's age" can be mathematically written as: z =2 x ---------------------------(1)
The next statement "Gina's brother is half Gina's age" can be mathematically written as y =  ---------------------------------------(2)
 ---------------------------------------(2)
Then the next statement "the sum of their ages is 42" can be mathematically written as: x + y + z = 42 ----------------------------(3)
We can now proceed to solve;
Substitute equation (1) and equation(2) into equation (3)
x + y + z = 42
x +   + 2x = 42
 + 2x = 42
Multiply through by 2
2x + x + 4x = 84
7x = 84
Divide both-side of the equation by 7
 =
 = 
x = 12
Therefore, Gina is 12 years old
 
        
             
        
        
        
I would love to help you but you haven’t given the sets