Vessel A Contains 50 gm of salt and 450 ml water
vessel B contains 110 gm of salt and 390 ml water
vessel C contains 160 gm of salt & 340 ml water
After the transfer of 100 ml from A to B
A will contain 360 ml water & 40 gm salt and B will contain 120 gm of salt and 480 ml water which makes B having 20% salt strength. After the transfer of 100 ml from B to C, C will Contain 180 gm of salt & 420 ml of water making it have salt strength = 30% After the final transfer of 100 ml from C to A, A will contain 70 gm of salt and 430 ml water making the salt strength in A = 14%
Alternate method:-
Answer = 14%