AC and DB are the same length. Set the two to equal each other and solve for y.
9y + 1 = 8y +17
Subtract 8y from both sides:
y + 1 = 17
Subtract 1 from each side:
y = 16
Now you know Y you can find the the length of DB:
DB = 8y +17 = 8(16) +17 = 128 + 17 = 145
EB is half of DB:
EB = 145 / 2
EB = 72.5