WH + 기로 했다
Let’s take a look at the pattern WH + 기로 했다. It is applicable to most question words and it is used to ask someone what they intend to do, where they intend to do something, who they intend to do something with, etc. We assume that the person is determined to do something in the future, that he has made up his mind before we ask the question. For example, a friend of yours was offered a job to spy someone’s daughter and chase her wherever she goes secretly. This kind of job is peculiar and since he agreed to do it, you ask how much did he agree to get or intend to get. The decision (how much to get) has been made before the question. Simple attach 기로 했다 to the stem of the verb.
얼마 받기로 했어?
How much are we getting paid for this?
How much money did you agree to get?
어디 기기로 했어?
Where are you planning to go?
누구한테 말하기로 했어?
Who are you gonna say it to?
(reveal a plan or tell a secret)
언제까지 숨기기로 했어?
Until when do you intend to hide?
이 돈으로 뭘 사기로 했어?
What are you going to buy with this money?