! which of the following is not a solution to the system of linear equations below? a. (5, 6) b. (–15, 12) c. (0, 3) d. (–10, –3)

To figure out which of the coordinates don't work, we need to substitute their values of x and y to figure out if they work or not. We will know they don't work if the result we get is something crazy like 2=25. 

Substitute the values of x and y from a


Now we simplify
 
Since this is true we know that the point (5,6) works. Now let's move onto B. 

Once again, we substitute. 


This simplifies to 

Since this is obviously not right, we know that is the point that doesn't work in this system of equations. 

140 students in the sixth grade

Step-by-step explanation:

75%= 105 sixth graders

since 75% is 3/4 of 100%

u can find 25% and then add that to 75% to find how many there are:

75/3= 25

105/3=35

25% = 35 sixth graders

25% *4 =100%

35*4= 140