Gradient Of A Straight Line

(B) Gradient of a Straight Line
If the points $A(x_1,y_1)$  and $B(x_2,y_2)$   lie on the straight line $y=mx+c$ , then gradient of ,the straight line
$$m=\frac{y_2-y_1}{x_2-x_1}or\frac{y_1-y_2}{x_1-x_2}$$