A flask is full of 20% sulphuric acid solution. A part of this 20% sulphuric acid solution is replaced by a 4% sulphuric acid solution and in this process 10% sulphuric acid solution is obtained. What fraction of 20% sulphuric acid solution is replaced from the flask?
1
(7/8)
2
(2/5)
3
(3/5)
4
(5/8)