frac{change~in~y}{change~in~x}\) To determine the gradient of a line: choose any two points on the line draw a right-angled triangle from one to the other, using the line as the hypotenuse ...

Now use the information you already have about finding the equation ... shown in these triangles. Remember, to find the equation of a line you need a point \((a,b)\) and the gradient \(m\).