To solve this we are going to use the half life equation 

Where:

 is the initial sample

 is the time in years

 is the half life of the substance

 is the remainder quantity after 

 years 
From the problem we know that:



Lets replace those values in our equation to find 

:




We can conclude that after 1600 years of radioactive decay, the mass of the 100-gram sample will be 
91.7 grams.
 
        
        
        
You have the polygon MNOPQR which can be expressed as two rectangles pasted one next to each other.
To see the two rectangles in the picture, you can draw a line parallel to segment MR througn point N.
From the original picture you can state the dimensions of both rectangles.
Call S, the point where the line that you drew intercepts the segment RQ.
Then one rectangle is MNSR and the other rectangle is OPQS.
The measures of the sides of the rectangle MNSR are: 
- the length of MN = length of SR = base
- the length of MR = the length of NS.= height
So its area is base * height, which you can all A1.
The measured of the rectangle OPQS are:
- segment OP = segment SQ = segment QR - segment SR = base
- segment PQ = segment OS = height
So its area is base * height, which you can call A2.
Then the area of the polygon MNOPQRS is A1 + A2. One of them is 9 u^2 and the other is what the answer is asking for, and that you have calculated above.
With this procedure you can tell the value needed.    
 
        
             
        
        
        
Answer:
10
Step-by-step explanation:
<em>Since it given that:</em>
<em>x = 7 and y = 3</em>
<em>We can substitute x and y:</em>
<em>(7-3) + 2(3)</em>
<em>7 - 3 = 4</em>
<em>4 + 2(3)</em>
<em>2(3) = 6</em>
<em>4 + 6 =10</em>
<em>Thus the answer is 10.</em>
<em />
<em>[RevyBreeze]</em>
<em />
 
        
                    
             
        
        
        
Percent is out of 100, and 25*4=100. So multiply 16*4=64, so the answer is 64%
        
                    
             
        
        
        
Answer:
Infinite solutions.
Step-by-step explanation:
If an equation is an identity, then there will be infinite solutions that the identity will have.
Let, us assume that an identity equation is given by
(a + b)² = a² +2ab + b².......... (1)
Now, putting any real values of a and b the identity will be satisfied.
Therefore, there are infinite solutions for an identity equation. (Answer)