Respuesta :

Quadrilateral LMNO is a rhombus ( the diagonals bisect each other ).
The system:
y = 3 x
y + 12 = 6 x
3 x + 12 = 6 x
6 x - 3 x = 12
3 x = 12
x = 12 : 4
x = 4
y = 3 * 4
y = 12
Answer: C ) 12