Respuesta :
					                   4x-y= -21
y= 4x+21
when x= 0 then y = 21
when y = 0 then x= 4.25
(0,21) (4.25,0 ) are solutions.
					                
					             y= 4x+21
when x= 0 then y = 21
when y = 0 then x= 4.25
(0,21) (4.25,0 ) are solutions.