What is the use of a divider

The use of a divider is to divide things/people.

Using "h" to represent the height and "i" as the number of inches the city is falling after each year, we can construct an equation. We know that the city begins at -72 inches, as it is that far below sea level. After one year, it drops (2*1) inches, or 2 inches after that first year. After two years, the fall would be (2*2) inches, or 4 inches. Thus, the full equation would be "h = -72 - 2i".