Which property of real numbers is demonstrated by the equation 12+0=12 ?

What is the sum of these mixed numbers 4 2/3+ 3 1/9

Factor the polynomial expression x6 – x3 – 20

Will mark 50 show all what is the solution to the system of equations? use the substitution method and show your work. -5x+y= -3 -15 x+3y=7 explain what your answer in part (a) tells you about the association of the lines in this system.