A ↔ B ↔ C ↔ D ↔ E ↔ F
8 7
???
AB + BC + CD = AD <em>segment addition postulate</em>
+ 8 + 7 = AD
+ 15 = AD
AD + 60 = 4AD
60 = 3AD
20 = AD
AB = =
= 5
DE = =
= 4
CD + DE + EF = CF <em>segment addition postulate</em>
7 + 4 + EF = CF
11 + EF = CF
Answer: 11 + EF
Note: You did not provide any info about EF. If you have additional information that you did not type in, calculate EF and add it to 11 to find the length of CF.