Solve, Using the Substitution Method, and Check $\begin{array} { c } 3 x + 4 y = 63 \\x = y\end{array}$

Multiple Choice

Solve, using the substitution method, and check. $\begin{array} { c } 3 x + 4 y = 63 \\x = y\end{array}$

A) (-63, -63)
B) (10, 10)
C) (14, 9)
D) (6, 6)
E) (9, 9)