4. Solve the system of equations \( \left\{\begin{array}{l}y=-5 x-20 \\ y=3 x+12\end{array}\right. \)

To solve the system of equations, we can set the two expressions for \( y \) equal to each other since they both represent \( y \): \[ -5x - 20 = 3x + 12 \] Now, let's combine like terms. First, add \( 5x \) to both sides: \[ -20 = 8x + 12 \] Next, subtract 12 from both sides: \[ -32 = 8x \] Now, divide both sides by 8: \[ x = -4 \] Now that we have \( x \), we can find \( y \) by substituting \( x \) back into either equation. Using the second equation: \[ y = 3(-4) + 12 = -12 + 12 = 0 \] So the solution to the system of equations is \( (x, y) = (-4, 0) \).