To write this equation, you need use the formula y=mx+b.
m represents the slope and b represents the y intercept.
The y intercept is the point where the line touches the y axis. In this case, the y-intercept is 1.
The slope is just rise over run from one coordinate to another. The slope is 2/-1 which could be simplified as -2. The slope just means that we are going up 2 and left 1 to get to a new coordinate.
The equation is y=-2x+1
Have a good day! :)