Environmental Chemistry Question

[AndrewGonzales]

This is my first time using this website. I have an undergraduate background in chemistry and I currently work in healthcare. Can anyone tell me why there are negative numbers listed and 0s are listed? I understand that the ionic charges are different.

SO₄-2 + H+ CH₂O ⇌ HS- + CO₂ + H₂O

1 S, 5 O, 2H, 1 C 1 S, 1 C, 3O, 2H

0 SO₄^-2 + 4 H + -1 CH₂O = -0 HS^- + -1 CO₂ + H₂O

[ChenBeier]

I also dont know either.
The first equation 7n first line is not balanced.
In second line the atoms left and right are counter. The doesn't fit.
The 3rd. line make no sense for me. Zero I have never seen in chemical equations.