Which equation has infinitely many solutions?
12 + 4x = 6x + 10 – 2x
5x + 14 – 4x = 23 + x – 9
x + 9 – 0.8x = 5.2x + 17 – 8
4x – 2x = 20
12 + 4x = 6x + 10 – 2x
5x + 14 – 4x = 23 + x – 9
x + 9 – 0.8x = 5.2x + 17 – 8
4x – 2x = 20