ok so slope is y2-y1/x2-x1. the question is asking you to find the value of x1 that will make the slope 7. plug in your coordinates to get (7-(-7))/(4-s)=7, then you simplify to get 14/(4-s)=7, multiply both sides by (4-s) to get 14=7(4-s), divide both sides by 7 to get 2=4-s, and then solve to get that s=2. hope this helps!
