The slope intercept form is y = mx + b so the slope is m and the slope in this case is -2.5. Now we substitute that in the equation. Well use the first set of ordered pairs for x and y. So now we have: -7 = -2.5(7) + b. When you solve for this you should get: -7 = -17.5 + b. Now you solve for the last part and you get: -7 = -17.5 + 10.5. So the Answer is: y = -2.5x + 10.5