you must use this question number 9 ,which i got the answer for (sed 's/,[^,]*,[^,]*,[^,]*,/,/' mountainList.txt ), to answer my actual question. This means MY QUESTION IS NOT NUMBER 9 IT IS NUMBER 15. I have the answer for number 9. I just need to make it back-reference. This is what I need help with.

Please also check your answer in your terminal to guarantee it works.

Thank you (:

15) Now can you write a command to finish task 9) using sed with back reference? Useful Links: [1] Introducing Regular Expression - Capturing Groups and Back-references expressions/9781449338879/ch04.html attpsillwy afaroksonline co ingregular 9) Use sed to remove the middle three fields in each line of "mountainList.txt Hint: Think about the meaning of regex ' Sample Output Brasstown Bald, Union County Rabun Bald, Rabun County Dick's Knob, Rabun County Hightower Bald, Towns County Wolfpen Ridge, Towns and Union Counties Blood Mountain, Union County Tray Mountain, Towns County Grassy Ridge, Rabun County Slaughter Mountain, Union County Double Spring Knob, Rabun County Coosa Bald, Union County 15) Now can you write a command to finish task 9) using sed with back reference? Useful Links: [1] Introducing Regular Expression - Capturing Groups and Back-references expressions/9781449338879/ch04.html attpsillwy afaroksonline co ingregular 9) Use sed to remove the middle three fields in each line of "mountainList.txt Hint: Think about the meaning of regex ' Sample Output Brasstown Bald, Union County Rabun Bald, Rabun County Dick's Knob, Rabun County Hightower Bald, Towns County Wolfpen Ridge, Towns and Union Counties Blood Mountain, Union County Tray Mountain, Towns County Grassy Ridge, Rabun County Slaughter Mountain, Union County Double Spring Knob, Rabun County Coosa Bald, Union County