Find resistance of final solution

V1 litre of solution A (Resistance = 500 ohm) is mixed with ​V2 litre of solution B (Resistance = 100 ohm). Resistance of the final solution is 80 ohm, then (V2/V1) will be (using same cell) :
(A) 1
(B) 2
(C) 3
(D) 4

answer is C