The equation will have the form y=ax+b. a is the slope, and b is the y value at x=0.
The slope is -2 (that's our a), which you can see from the two given points. If x progresses from -3 to -2, y goes from 3 to 1. At x=0, the line crosses through y=-3 (that's our b)
So our generic form y=ax+b for this line is y=-2x-3
