Given:

Present State of Electron = 6

When an electron drops from nth shell to ground state, the number of lines produced is given by = {n× [n-1]} / 2

So, in the question the electron drops from 6^th state to ground state.

So, number of lines produced in this transition is = {6× [6-1]}/2

=15

So, the lines produce in the transition is shown as below: