Which equations are in standard form? Check all that apply

1) y = 2x + 5
2) 2x + 3y = –6
3) –4x + 3y = 12
4) y = (3/2)x – 9
5) (1/2)x + 3 = 6
6) x – y = 5
7) 5x + 3y = (1/2)