Solve using substitution.

To solve the system of equations using substitution, we will substitute the expression for \( y \) from one equation into the other.

We have the two equations:

1. \( y = -3x + 8 \)
2. \( y = -x - 4 \)

Since both equations equal \( y \), we can set them equal to each other: \[ -3x + 8 = -x - 4 \]

Next, we will solve for \( x \). First, we can add \( 3x \) to both sides: \[ 8 = 2x - 4 \]

Now, we will add \( 4 \) to both sides: \[ 12 = 2x \]

Next, divide both sides by \( 2 \): \[ x = 6 \]

Now that we have the value of \( x \), we can substitute it back into one of the original equations to find \( y \). Let's use the first equation: \[ y = -3(6) + 8 \] \[ y = -18 + 8 \] \[ y = -10 \]

So, the solution to the system of equations is: \[ (x, y) = (6, -10) \]

To summarize, the solution is \( (6, -10) \).