Hey there!
Let's start by solving for x.
Take the first equation, y = -3x - 7, and substitute in the second equation, y = x + 9, for y.
We now have:
x + 9 = -3x - 7
Add 3x to both sides.
4x + 9 = -7
Subtract 9 from both sides.
4x = -16
Divide each side by 4.
x = -4
Let's use the second equation, y = x + 9, to solve for x.
Put in the value we just solved for.
We now have:
y = -4 + 9
Simplify.
y = 5
Let's check our answer, starting with the first equation, y = -3x - 7.
Put in the values for x and y.
5 = -3(-4) - 7
5 = 12 - 7
5 = 5
Do the same with the second equation, y = x + 9.
5 = -4 + 9
5 = 5
The solution to the system of equations is (5, -4).
Hope this helps!
