Minimum number of Relations:-
The Answer is $5$. Please see my Reason behind it:-
1. $R_6$ and $E_5$ CAN be merged giving $1$ relation we cant merge with $E_3$, because its a strong entity even though the participation is total.
2. $E_1$ and $E_4$ Gives total of $1$ relation.
3. $R_1$ Will have its separate relation
3.$E_2$, $E_3$ , $R_3$, and $R_5$ can be merged.
4. $R_2$ will have separate table because of many to many (Doubt here)
Hence total $5$ tables we got.
