This isn't a table, but you can easily make it into one.
s          t
-2     -5.5
-1      -2.75
0         0
1        2.75
2        5.5
        
                    
             
        
        
        
The mean is the average of the numbers.
It is easy to calculate: add up all the numbers, then divide by how many numbers there are. 
Let the number of sit-ups you have to do Sunday be x. Then the sum of all sit-ups is
100+65+120+150+90+0+x=525+x.
The number of days is 7.
Thus, the mean is

You know that the mean number of sit-ups per day is 100, equate these two means and solve the equation:

Answer: 175 sit-ups
 
        
             
        
        
        
You're answers are a bit jumbled up but here is the answer:
T for Two
B for Blue
M for Moon Roof
F for four
G for Gray
NM for No Moon Roof... so
TBM
TBNM
TGM
TGNM
FBM
FBNM
FGM
FGNM
8 Possibilities
        
                    
             
        
        
        
Answer:
y = 2x + 1 --> linear
y = -4x + 7 --> non-linear
Not a solution for linear system.
Step-by-step explanation:
for (a), y = 2x+1, substitute the x and y values. keep in mind, that in a linear pair, (x, y). So, for the first equation you get:
7 = 2x3 + 1. This is correct, because 6 + 1 is 7. Therefore, (a) is linear.
for (b), we have to substitute our values again. You get:
7 = -4x3 + 7, which is
7 = -12+7, which is not true. So, (b) is not linear.
This means that for the linear pair (3, 7), it does not satisfy both equations, which means that it is not a solution for the linear system.