Someone explain what i ! i dont understand!

it says

find the indicated measure in abcd. explain your reasoning.

i am doing a quiz today and this is review work. i seriously need someone to explain this to me asap.

answer: there are x+184 pages in olivia's book.

step-by-step explanation:

let the total number of pages in the book which olive has already read be x.

then if olive has 184 pages left to read, then the total number of pages are in olive's book= pages she has read+pages she has left to read

therefore, the total number of pages in olivia's book=

hence, there are x+184 pages in olivia's book.

all it means is function 3