Part A: 
We see that this pair of equations has 1 solution. On a graph, the solutions of 2 (or more) lines is where the lines intersect. In this case, since these lines intersect 1 time, they have 1 solution. 
Part B:
As previously mentioned, the solutions of multiple lines is where the lines intersect. In this case, since they intersect at (4,4), that is the solution.
 
        
             
        
        
        
We are given table
Month :         1     2        3         4         5
Shoppers:   50  250   1250   6250  3250
so, we have 
first term =50

Second term =250

Third term =1250



now, we can find ratios

we can see that all ratios are same and 5
so, this is exponential 
so, option-D..........Answer
 
        
                    
             
        
        
        
Answer:
Mean = 1.57
Variance=0.31
Step-by-step explanation:
To calculate the mean and the variance of the number of successful surgeries (X), we first have to enumerate the possible outcomes:
1) Both surgeries are successful (X=2).

2) Left knee unsuccessful and right knee successful (X=1).

3) Right knee unsuccessful and left knee successful (X=1).

4) Both surgeries are unsuccessful (X=0).

Then, the mean can be calculated as the expected value:

The variance can be calculated as:

 
        
             
        
        
        
I think it is $0.27 because 15% of 1.80 is 0.27
        
             
        
        
        
When dilation is about the origin, as it is here in every case, the image point coordinates are the original (pre-image) coordinates multiplied by the scale factor.
1. Multiply every coordinate value by 5:
... W' = (-5, 10), X' = (-15, -5), Y' = (25, -5), Z' = (15, 10)
2. Multiply every coordinate value by 1/3:
... A' = (-2, 5), B' = (0, 5/3), C' = (1, 10/3)
3. A' = (2, 8), B' = (6, 2), C' = (2, 2)
4. The image coordinates are 5 times the original coordinates, so ...
... the scale factor of the dilation is 5.