Which systems of equations have enough variables and equations to potentially solve the system? Select all that apply.

1) {3x−4=y
−5x+7=y

2) {3x−4y=8z
−3x+6y=4z

3) {2x−4y=8
−2x+6y=14

4) {y=2x−4
y=−9z+6

5) {y=2x−4
y=−x+6

please get me to 10points and thank you! :)