PLEASE HELP I BEG YOU! I will mark brainliest if right explain!!!

9514 1404 393
Answer:
(d) 8
Step-by-step explanation:
Corresponding sides are proportional.
ED/EG = EC/EF
(6x +3)/17 = (8x -1)/21
21(6x +3) = 17(8x -1)
126x +63 = 136x -17
80 = 10x . . . . . . . . . . . add 17-126x
8 = x . . . . . . . . . . divide by 10