Two point charges (-q) and (+4q) are placed at separation 'r'. Where…

at separation 'r' from (-q) on the extreme side of -q.

at separation 'r' from (4q) on the extreme side of 4q.

at separation $\frac{r}{2}$ from (-q) in between the two charges.

at separation $\frac{r}{4}$ from (4q) in between the two charges.