I did this but got a different answer to it , but most likely it’ll be A , Hope this helps !
Answer:

multiply either sides by 3:

divide either sides by πr² :

Chelsea has 55 art brushes. She has this manu because Monique has 5 necause 11x5 is 55. 55 plus Monique's 5 is 60 brushes in total. Have a nice day :)