$\begin{array}{ccccc}\text{Sol. Student}& \text{Economics (300)}& & \text{Accounts (200)}& \\ & \text{Percentage}& \text{marks}& \text{Percentage}& \text{Marks}\\ \text{Sachin}& 30& 90& 25& 50\\ \text{Ashish}& 10& 30& 20& 40\\ \text{Tanwi}& 15& 45& 10& 20\\ \text{Ankit}& 10& 30& 10& 20\\ \text{Ramesh}& 20& 60& 30& 60\\ \text{Suresh}& 15& 45& 5& 10\end{array}$
In case of Ramesh, the marks scored by him in Economics, Finance and Accounts are $20\%,20\%and30$ respectively out of the total marks scored by all the students put together.
$\therefore 20\%$ of the total marks of all the students in Economics $=30\%$ of the total marks of all the students in Accounts
$\therefore$ The ratio of the total marks scored by all six students put together in Economics to that of Accounts will be 3 : 2.
For simplicity, assume that the total number of marks obtained by all of them in Economics be 300 and in Accounts be 200.
Now the results can be tabulated by taking the marks in the required ratio as shown above.
$\therefore$ There are only 2 students satisfying the criteria.