Expression 1: left bracket, "y" , "x" , "y" , negative "x" , right bracket less than left bracket, "x" , "y" , negative "x" , "y" , right bracket left brace, left bracket, negative 20 , 0 , negative 20 , 0 , right bracket less than or equal to "x" less than or equal to left bracket, 0 , 20 , 0 , 20 , right bracket , right brace left brace, left bracket, negative 20 , 0 , 0 , negative 20 , right bracket less than or equal to "y" less than or equal to left bracket, 0 , 20 , 20 , 0 , right bracket , right bracey,x,y,−x<x,y,−x,y−20,0,−20,0≤x≤0,20,0,20−20,0,0,−20≤y≤0,20,20,0