You would take two points and use the slope formula
Y2-y1/x2-x1
So I took the points (0,0) and (1,5)
5-0/1-0 5/1 5= the slope
So now we know y=5x+b and since it shows us on the graph where the line crosses the y axis we know the y intercept will be zero because it crosses at 0. When the y-intercept is 0 we don’t even need to list it.