y = ax + b
Where a is constant.
For example, you might have seen an equation like this: 2x+4, and here, a = 2, and b = 4.
The constant, b, determines where the y-intercept is, where the graph of the equation hits the y-axis. If you leave out the b constant (or set it as b = 0), the graph for the equation will start at the origin (0, 0).
