MATH RADICALS

Hi! Our names are Jamie and David. We ride mountain bikes. I have a Trek Y frame and Jamie has a Trek 7000. One thing that we both share in common is that we both enjoy trial riding, a sport in which you use your bike to jump over difficult obstacles, i.e. tables. This is called a clearing object. A dab is when you have to put your foot down to keep balanced to clear an object. For each dab you make you lose a point.
Problem: Joe is a trial's rider. If he dabs x times on a course worth ten and his average number of dabs for these courses was 2x how many times did Joe dab on his first run if his total score is 18?