Given that we have a set of known points, we can take two of them to calculate the slope of the line as follows:
m = (y1 - y2) / (x1 - x2)
Let (x1 , y1) = (0, -3) and (x2 , y2) = (-1, -2) (First two points in the table), then:
m = (y1 - y2) / (x1 - x2) = [-3 + 2]/[0 - (-1)] = -1/1 = -1
Using the point-slope equation, we can write:
y - y1 = m(x - x1), then
y - (-3) = (-1)(x - 0) = -x
which can be written as:
y = -x - 3 (Equation of the line)
The intercept, we can obtain its value by setting x = 0, then the intercept is:
b = -3.