A line passes through the point (3, -6) and has a slope 2 of . Write an equation for this line.

First, the problem tells us that the slope is 2, so from the equation

y=m x + b

we know m=2. We have one more info that is not exploited, which we shall use to find "b":

-6 = 2 * (3) + b = 6 + b.

Hence

b = -12. And all in all

y = 2 x - 12. Note the "-" sign to signify that "b" is negative.