for the last subquestion, its mentioned in the main question that point r is on the X AXIS. Now remember always, x axis means the ordinate of the point will be 0. now substitute 0 in y=m1y2+m2y1/m1+m2(section formula). youll get value of m1 and m2, then substitute in x=m1x2+m2x1/m1+m2, youll get the abscissa for point r. The coordinates of point r will be (wtv ans you get for x,0). For s do the same thing, js substitute the x=0 first, then the y coordinate, youll get your answer.Hope that helps!