To solve the system of equations using substitution, we start with the given equations:
- \( 4x - 10y = 18 \)
- \( y = -5 \)
Since \( y \) is already expressed in terms of a constant, we can substitute \(-5\) for \(y\) in the first equation.
Substituting \( y = -5 \) into the first equation:
\[ 4x - 10(-5) = 18 \]
Now simplify the equation:
\[ 4x + 50 = 18 \]
Next, isolate \(4x\) by subtracting \(50\) from both sides:
\[ 4x = 18 - 50 \]
\[ 4x = -32 \]
Now, divide both sides by \(4\) to solve for \(x\):
\[ x = \frac{-32}{4} \]
\[ x = -8 \]
Now we have the solution for the system of equations:
\[ x = -8, \quad y = -5 \]
Therefore, the solution is \( (x, y) = (-8, -5) \).