The easiest way to solve this is by elimination.
3x - y = 6
6x + y = 21
Since you have a negative and positive y with the same coefficients (1), they cancel, and you add the other terms so it would look like:
9x = 27
Then solving for x leaves you with x = 3
Then you take the x value of three and plug it into to either of the equations, so
3(3) - y = 6
9 - y = 6
subtracting 9
-y = -3
then dividing by -1
y = 3
so the solution is x = 3 y = 3 or (3,3)
Answer:
1
Step-by-step explanation:

Answer:
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Answer:
D and yes
Step-by-step explanation:
+ 1 = -3 If we multiply both sides of the equation by 4 will will get the second equation
(4)
+ (4) 1 = (4) -3
x + 4 = -12 We solve this for x by subtracting 4 from both sides.
x = -16
Plug -7 into both equations and you will see that it is a solution
+ 1 = -3
+ 1 = -3
-4 + 1 = -3
-3 = -3
x + 4 = =12
-16 + 4 = -12
-12 - -12