Angle AED = angle DEC
angle B = angle C
So....triangle AEB similar to triangle DEC
AB /EB = DC / EC
50 / 20 = 35 /EC
2/5 = EC / 35
(2/5) * 35 = EC
14 = EC
So
AE = AC - EC = 54 - 14 = 40
So
EC /ED = EB / AE
14/ ED = 20 / 40
14/ ED = 1/2
Which implies that ED = 28