I just taught you how to do this, it’s really simple, try it yourself! I’ll give instructions again.
Use the equation Y=mx+b where m represents the slope and b is the y-axis point.
Finding b is easiest, so we’ll do that first. Again, b is the y axis point. So where does the line cross the y axis? That is the vertical line on the graph. The line crosses at point (0,5) so 5 is your b value.
Next find your m value, or slope. The slope is simply rise/run. Which means start at the y axis value, and count how many places you need to go down to find a perfect triangle shape. You simple go down two points, and then over one point to reach a perfect triangle. Therefore since you go down 2, your rise is -2 and since you go over 1, your run is 1. Rise/run=-2/1, this simplified is just -2. So that is your m value.
Finally, plug these into y=mx+b and get your answer of
Y=-2x+5
Best,
jrodt