if ED=10 and DB=3x-8 whats the lenght of EB

Answer 1

There are in fact three cases.

Case 1: (seemingly obvious case)
E-----D--------B
ED=10
DB=3x-8
EB=10+3x-8=3x+2

Case 2:
E-----B-------D
ED=10
DB=3x-8
EB=10-(3x-8)=18-3x=3(6-x)

Case 3:
D-----E--------B
ED=10
DB=3x-8
EB=3x-8 - 10 = 3x-18=3(x-6)