Solve the System by the Substitution Method $$\begin{array} { l } x ^ { 2 } + y ^ { 2 } = 41 \\x + y = 9\end{array}$$

Multiple Choice

Solve the system by the substitution method.
- $$\begin{array} { l } x ^ { 2 } + y ^ { 2 } = 41 \\x + y = 9\end{array}$$

A) $\{ ( 5,4 ) , ( 4,5 ) \}$
B) $\{ ( - 5,4 ) , ( - 4,5 ) \}$
C) $\{ ( 5 , - 4 ) , ( 4 , - 5 ) \}$
D) $\{ ( - 5 , - 4 ) , ( - 4 , - 5 ) \}$