Opposed skill checks

Opposed skill check
Sometimes when you use a skill or feat, you are directly competing with a monster or another character. In these cases you make an “opposed” skill check. The DC is not a fixed number, but a skill check made by your opponent. For example, when you use Stealth skills to conceal yourself, the DC of your attempt is determined by a Spot or Listen check by any enemy trying to locate you. If the enemy has a Spot skill bonus of +7, then the DC you must beat with your combined modal Stealth is between 8 and 27 (a random number between 1 and 20 plus 7).

Note the above table was created from combining both the d20 vrs d20 linear and bell curve tables, to represent in game results. The final difference between players skill and the opposed skill check (excluding both d20 roills) determines the odds of success to failure or just the percentage of success.