The distance formula is this: d=sqrt((y_2-y_1)^2+(x_2-x_1)^2), where (x_1,y_1) are the coordinates of the first point, (x_2,y_2) are the coordinate of the second point, and d is the distance between the two points.
Let's say (-1,7) is the first point, and (2,12) is the second point Note that it doesn't matter which one we call the first or second point