1. Carter sold 9 of his video games online. The next day, he sold 27 video games. He collected a total of $900. If he charged the same amount for... dfghjhygtfrdesdrftgyh

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)