[tex]2x+y=0\qquad\text{subtract 2x from both sides}\\\\y=-2x\\\\\text{Put it to the second equation}\ 5x+3y=-11:\\\\5x+3(-2x)=-11\\\\5x-6x=-11\\\\-x=-11\qquad\text{change the signs}\\\\\boxed{x=11}\\\\\text{Put the value of x to the first equation:}\\\\y=-2(11)\\\\\boxed{y=-22}\\\\Answer:\ \boxed{x=11\ and\ y=-22}[/tex]
