Jon decides to take up baseball. He can throw a fastball at 80 miles per hour.  He goes through intense training 4 times for 4 weeks each time and at the end of the last one he can throw a ball 20% faster. How much speed (in mph) did he gain per week, assuming he gained an equal amount of speed (in mph) each week? Give me reasons, before answering the question
He threw the ball 80 * .2 = 16 mph faster. He was training for 4 * 4 = 16 weeks. So he gained 16 / 16 = 1 mph per week. So the final answer is 1.