Originally Posted by Salamandrine

Should be an RX100 crank, which is 130 BCD. If they are standard and not anything oddball (I can't remember) you should be able to swap out the chainrings for 38/48.

However, I would suggest simply replacing the 7 speed cassette with a wider range one, and getting a long cage rear derailleur. It's simpler and more effective, easier and typically cheaper. All you need is a cassette, chain, rear derailleur.