Step-by-step explanation: CD=CE+ED ED is 5 and it is also the midpoint meaning it is 1/2 of the value of the line. Therefore CD is 10, BC=BD+CD CD as we know is 10 and D is the mid point meaning it is also 1/2 of the value of BC. 10+10=20, AB=AC+BC, BC is 20 so AC must also be 20;therefore AB is 40
