OK to solve this, we have to solve each system presented through elimination or substitution and find which one is equivalent to that of the teacher's!
First let's solve for the teacher's:
-2x+5y=10
-3x+9y=6
Solve by substitution (I think elimination might be easier to do for this one, but I don't really remember 100% sorry!)
Isolate the x (or y) variable in the first equation
-2x+5y=10
-2x=10-5y

Substitute x into the next equation and solve for y
-3(10-5y/2)+9y=6
3*10-5y/2+9y=6
(multiply both sides by 2)
3(10-5y)+18y=12
30-15y+18y=12
30+3y=12
3y=-18
y=-6
Substitute in x
x= -10-5(-6)/2
x=-20
TEACHER'S ANSWER (-20,-6)
GOKU
x-3y=-2
-2x+5y=-7
Do the same as above
Solve for x
x-3y=-2
x=3y-2
Plug in
-2(3y-2)+5y=-7
4-6y+5y=-7
4-y=-7
-y=-11
y=11
x=(3(11)-2)
x=31
GOKU'S ANSWER (31, 11)
SELINA:
-5x+14y=16
-3x+9y=12
One last time!! :)
-5x+14y=16
-5x=16-14y
x=(16-14y)/-5
-3(-(16-14y/5)+9y=12
3*16-14y/5+9y=12
3*16-14y+45y=60 
48-42y+45y=60
48+3y=60
3y=12
y=4
x=-(16-14(4))/5
x=8
SELINA'S ANSWER
(8,4)
So neither Goku or Selina got the same answer as the teacher
 
        
        
        
Answer:
x≈231.123
Step-by-step explanation:
1) Make a ratio 314/2512= x/1584
2) Use the concept of cross multiplication and get 314*1584=2512x
3) Use Algebra:
314*1584=497,376
497,376/2152=2512x/2152
x≈231.123
 
        
             
        
        
        
Answer:
Both answer are "B" im pretty sure. :)
Step-by-step explanation:
 
        
             
        
        
        

 and 

, or as a rounded decimal 85.28 and 85.28. 
To find the smallest possible sum of roots for any product, the answer is always whatever numbers are closest together. This fact can be derived by the fact that the greatest area we can enclose with a given length is a perfect square. So we can take the square root of 7272 and use that, since they will be exactly the same number. 
If you are looking for whole numbers, you would have to go up or down until you find a factor of 7272 closest to the square root. In this case that would be 72 and 101. 
 
        
             
        
        
        
Answer:
25.56% or $11.50
Step-by-step explanation:
I took it and put it in a sales tax calc.