How to Adjust Comps Correctly

[Ethan Rapier]

Hello everyone, 

My business partners and I are looking to purchase our first flip. We have been recently looking at a few properties and had comps sent to us but, adjusting them have proven to be a challenge. 

The issue I'm running into is how to adjust the value of comp based on if it has an extra bed room, fireplace, etc. then my subject property. I can't seem to figure out what that extra room or feature is worth to adjust up and down? Could anyone please advise how they adjust their comps. If it helps, I've been basing these off how J.Scott does his in his book "The Book on Flipping Houses." Thank you.