Can you explain how to find straight line equations?

Straight line equations always come in the form y=mx+c, where m is the gradient of the line (how steep it it) and c is the point where the line crosses the y axis (the y intercept).If you are given two points say 1 - (2, -4) and 2 - (6, 8) we can find the equation of the line that runs through them.First we find the gradient - this is the change in y over the change in x, (y₂ - y₁) / (x₂ - x₁)Here this is (8- (-4)) / (6 -2) = 12/4 = 3Next we plug this into the form of the equation and use one of the points to find ceg using point 1, -4 = 3 x 2 + cwe then re arrange -4 - 6 = cTherefore c = -10Finally we use all the values we have found to create the straight line equation,y=3 x -10