First write down the formula which is: y=mx+b
M is the slope and B is the y-intercept
The slope is rise/run, so if your slope is 2 then, 2 is your rise and 1 is your run
In order to find the y intercept you have to plot the points given in your question and and move your rise down and moving the run to the left until you find your y-intercept
Once you find the y-intercept, just plug in your slope and y-intercept