well ive got thatOAB is a triangle with OA =and OB =a; C is the mid-point of OB, D is the mid-point of AB and E is the mid-point of OA; OD and AC intersect at F.b

If AF =hAC and OF =kOD show thath=k= 2/3

AC = 1/2(-b)a

and

OD = (1/2)- (1/2)ba

AF = h/2(-b)a

and

OF = k((1/2)- (1/2)b)a

and this what i think i need to do get the intersection

h/2(-b) = k((1/2)a- (1/2)b)a

but i dont know where to go from there ?