Slope intercept form is y = mx + b
Y = the y-value [ for example, in the pair (9, 8), 8 would be the y-value
M = slope [ to find slope, use the equation (y2-y1)/(x2-x1) ]
X = the x-value [ for example, in the pair (9, 8), 9 would be the x-value
B = the y-intercept; when x is 0, whatever y is, that's your y-intercept
Now that you know what the variables mean, plug them into your equation.