Answer
ED is 10
DB is 10
EB is 20
Work Step by Step
The diagram shows $\overline{ED}$ and $\overline{DB}$ are congruent, so we obtain:
ED=DB
$x+4=3x-8\longrightarrow$ substitute and solve for x
$x+4+8=3x-8+8\longrightarrow$ add 8 to each side
$x+12=3x\longrightarrow$ simplify
$x+12-x=3x-x\longrightarrow$ subtract x from each side
$12=2x\longrightarrow$ simplify
$12\div2=2x\div2\longrightarrow$ divide each side by 2
$6=x \longrightarrow$ simplify
Substitute for x to find each length.
ED=$x+4=6+4=10$
DB=$3x-8=3(6)-8=18-8=10$
Use the Segment Addition Postulate
EB=ED+DB=$10+10=20$
