Use either the Annex or CAP 697 page 30 which has a better print quality.

Enter at 2000 NGM……… ZERO wind trip time…...   4.830hrs

                                    25kt head wind trip time..           5.150hrs

                                                An increase of……               0.330hrs

As a percentage of the still air time:+ 0.330 x 100 = + 6.85 %

4.830