It's been years since I've had to use algebra and this problem is driving me crazy.

I have point A(5651,4768) and point B(5649,4742).

I want to find a point C(x,y) that is distance 15 from point A, along the line AC.

I've sort of figured it out, but I don't know how to express Cx=?? and Cy=?? in equation form.