Put the of value of 3 different fields to 1 item properties

Dear all,

 I would like to ask whether we can put the of value of 3 different fields to 1 item properties. For example: I have a set of fields to ask users whether they need reimbursement for their travel expense. I have a Yes/No field. If I tick "Yes", then 2 other fields, drop down of choice of currency (e.g. USD, EUR, GBP, etc) and the amount field (a number field) come up. I have a column item on the list called "travel expense", and if the user fills in the data "USD 1000" then the "travel expense" column will be "USD 1000".

Is there any way to do this?

Thanks!