Help with this vector question?

Question

ok this seems like an easy question but its confusing me.

i cant draw the diagram so ill explain it.

ABCD is a parallelogram with AB= vector x, BC=vector y.

BC is the horizontal line.

Another line BE, joins point B to the line AD such that AE:ED=1:2

A diagonal line connects point A to C and intersects with line BE at a point F.

Given that BF=vBE

a). Express vector BF in terms of x, y and v.

b) Show that vector AF= (1-v)x + (1/3)vy.

c) Use the expression of AF to find the value of v.

part a and b are pretty easy but its part c thats confusing. because we have to use the expression.

Answer 1

a. AD = y

then AE = y/3

-x + y/3 = BE = BF/v

thus

BF = -vx + vy/3

AF = x + BF = (1-v)x + vy/3

.. . .

i cant seem to obtain part c also .. . .. .

unless we observe that AF is a fraction of AC = x + y

then (1 - v) should equal v/3 for it to be a fraction of x + y

solving.. . .

1 - v = v/3

v = 3/4