For the Given System of Equations, Which Method Would Be $x+y=12$

Multiple Choice

For the given system of equations, which method would be the most efficient method to use when solving the system of equations: substitution, addition, or either?
- $x+y=12$
$4 \mathrm{x}+9 \mathrm{y}=41$

A) addition
B) substitution
C) either