Solve the System by the Substitution Method $$\left\{ \begin{array} { l } 5 x + 3 y = 80 \\2 x + y = 30\end{array} \right.$$

Multiple Choice

Solve the system by the substitution method.
- $$\left\{ \begin{array} { l } 5 x + 3 y = 80 \\2 x + y = 30\end{array} \right.$$

A) $\{ ( x , y ) \mid 2 x + y = 30 \}$
B) $\{ ( 10,10 ) \}$
C) $\varnothing$
D) $\{ ( 0,10 ) \}$