Use the Substitution Method to Solve the Following System $$\left\{ \begin{array} { c } 7 a + 9 b = 69 \\a = 21 - 5 b\end{array} \right.$$

Multiple Choice

Use the substitution method to solve the following system. If the equations of the system are dependent, or if the system is inconsistent, so indicate. $$\left\{ \begin{array} { c } 7 a + 9 b = 69 \\a = 21 - 5 b\end{array} \right.$$

A) $( 6,3 )$
B) $( 6 , - 3 )$
C) $( - 6,3 )$
D) The equations are dependent.
E) The system is inconsistent.