Why are these terms not monomials?

And if they aren’t monomials, what type of polynomial are they?

You need to solve a system of equations. you decide to use the elimination method. which of these is not allowed? 3x - 2y = 7 3x + 4y = 17 equation 1 equation 2

Factor the polynomial, if possible. if the polynomial cannot be factored, write prime. 9n^3 + 27n^2 – 25n – 75

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.