Answer:
The solution is x = -2, y = -3
Step-by-step explanation:
Let's start with the equation 3x + y = -9
Substitute the y for 5x+7 seen in the second equation
Now you have 3x + (5x+7) = -9
Lets solve:
Let's add the x's
Now we have 8x + 7 = -9
Substracy seven from each side
Now we have 8x = -16
Now let's divide 8 on each side
Now we have x = -2
Now lets plug in -2 to the second equation
The second equation is y = 5x+7
When we plug in -2 we get y=5(-2)+7
We multiply 
We now have y = -10+7
Add
y = -3
The solution is x = -2, y = -3
 
        
             
        
        
        
A) 2 2/9
The answer would of course be positive because two negatives make a positive.
It would only be 6 4/9 if you added when here it states the obvious for you to subtract.
Hope this helped PLEASE MARK BRAINLIEST!!
 
        
             
        
        
        
Answer:
1.
-3x + 8y = -5
6x + 2y = -8
Set the equations to a common variable.
-3x + 8y = -5 → 8y = 3x - 5 → y = 3/8x - 5/8
6x + 2y = -8 → 2y = -6x - 8 → y = -3x - 4
Set the equations equal to each other.
3/8x - 5/8 = -3x - 4
Combine like terms.
3x + 3/8x = -4 + 5/8
3.375x = -3.375
Divide by 3.375
x = -1
Plug x back in to find y.
-3x + 8y = -5
-3(-1) + 8y = -5
3 + 8y = -5
8y = -8
y = -1
answer: (-1, -1)
2.
3x + 2y = -16
-3x - 8y = 46
Set the equations to a common variable.
3x + 2y = -16 → 2y = -3x - 16 → y = -3/2x - 8
-3x - 8y = 46 → -8y = 3x + 46 → y = -3/8x - 23/4
Set the equations equal to each other.
-3/2x - 8 = -3/8x - 23/4
Combine like terms.
-9/8x = 9/4
or
-1.125x = 2.25
Divide by -1.125
x = -2
Plug x back in to find y.
3(-2) + 2y = -16
-6 + 2y = -16
2y = -10
y = -5
answer: (-2, -5)
 
        
                    
             
        
        
        
-2.7639320225 is the exact when estimated -3 hope this helped if can pls mark as brainliest have a great day!
 
        
             
        
        
        
Answer:
you will 180 pints of the 100% juice and 540 pints of the 40% juice
Step-by-step explanation:
in order to get a 55% mixture you must combine 1 100% and 3 40%
100 + 120 = 220 then divide by 4 and you get 55% juice 
now you must use 180 100% juice and 540 40 % juice to make 180 pints
you need this because the ratio is 3 40% to every 1 100%