Which of the following equations are equivalent to -2m - 5m - 8 = 3 + (-7) + m?
1. -15m = -4m
2. -7m - 8 = m - 4
3. -3m - 8 = 4 - m
4. m - 4 = -7m - 8
5. -8 - 7m = -4 + m
6. -8 - 3m = 4 - m