To solve the system of equations using substitution, we first substitute the value of \( x \) from the second equation into the first equation.
Given:
- \( 7x - 9y = -5 \)
- \( x = 7 \)
Now, substitute \( x = 7 \) into the first equation:
\[ 7(7) - 9y = -5 \]
Calculating \( 7(7) \):
\[ 49 - 9y = -5 \]
Next, we need to isolate \( y \). Start by subtracting 49 from both sides:
\[ -9y = -5 - 49 \]
This simplifies to:
\[ -9y = -54 \]
Now, divide both sides by -9:
\[ y = \frac{-54}{-9} = 6 \]
So, we have found \( y = 6 \) and \( x = 7 \).
The solution in coordinate form is:
\[ (7, 6) \]