finding midpoint

Question

 

Did I solve this correctly:

 

                      E

 

                                   2x

__________________________________________________

A          D            B                    C

 

 

if AC = 12, then AB = 6 and AD = 3

 

if DC = 15, then AC = 20

 

(B is the midpoint of AC, DE bisects AB)

 

thanks

Answer 1

looks correct

although it's uclear what "2x" refers to