Respuesta :
I would say the first row.
{(5,4), (2,3, ( 1,1), (2,4)}
because (1,1), the 'x' and 'y' are the same.
{(5,4), (2,3, ( 1,1), (2,4)}
because (1,1), the 'x' and 'y' are the same.