Variables-
# of hours: h
Overall snow depth: S
Town 1: S₁ = 4 + 6h
Town 2: S₂ = 8 + 2h
To find when S₁ and S₂ are equal, set them equal to each other!
S₁ = S₂
4 + 6h = 8 + 2h
4 + 6h - 2h = 8 + 2h - 2h
4h + 4 = 8
4h + 4 - 4 = 8 - 4
4h = 4
4h / 4 = 4 / 4
h = 1
After 1 hour, they will both have the same depth of snow. Hope this helps! :)