You can put this solution on YOUR website! Good question. Since the rate of change is constant - it's constantly changing by (-0.5) - we know it's a linear equation. Linear Equations are written in the form: y = mx + b, where m is the slope, and b is the y-intercept. We already know the slope: -0.5. We also know the y-intercept from the data above because x = 0 when y = 9.5. Now we know the whole equation: