Answer:
(-3.25,3.75)
Explanation:
Thuis can be answered with either of two approaches: Graphing and Matematical. We'll do both:
Graphing
Graph both equations. It is helpful to use a free online graphing utility: DESMOS.
The attached graph reveals the intersection of the lines at point (-3.25, 3.75).
Matematical
Solve the equations be using substitution. Rearrange either equation to isolate one of the two variables (x or y).
Lets use the second, since y is already isolated, making the task simple and fast. But the other equation could also be used, if desired.
y=x+7
Now use this expression of y in the other equation:
9x+3y=-18
9x+3(x+7)=-18
9x +3x +21 = -18
12x = -39
x = -(39/12)
x = -3 - (3/12)
x = -3.25
Now use x= -3.25 in either equation tand solve for y:
y=x+7
y=(-3.25)+7
y = 3.75
The solution to this series of equations is (-3.25,3.75)