Please answer correctly

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

The diagram represents the polynomial 4x2 + 23x – 72. what is the factored form of 4x2 + 23x – 72? (4x + 8)(x – 9) (4x – 8)(x + 9) (4x + 9)(x – 8) (4x – 9)(x + 8)

y=2x−1 5x−4y=1 is (1,1)(1,1) a solution of the system?