This question needs more information like where point E is but I'm going to assume that point E is directly below point D
With that assumption, angle EDF should be (90°- 25°) which is 65°
tan 65° = opposite/adjacent
tan 65° = 10 yd/ DE
DE = 10 yd/tan 65°
DE = 4.7 yd (to the nearest tenth)
Remember to include a picture next time for greater clarity :)