People who exercise maintain target heart rates that are a percentage of their maximum heart rate. Maximum heart rate is R=220A, where A is the person's age and R is the heart rate in beats per minute. Complete parts a through c. (a) Find R for a person 40 years old; 80 years old. When A=40, the maximum heart rate R is heart rate R is beats per minute, and when A=80, the maximum beats per minute. (b) Sketch a graph of R 220A. Assume that A is between 40 and 80. Graph the inequalities. (c) Interpret the graph. What does the graph represent? Choose the correct answer below. Possible heart rates for ages 40 to 80 Possible heart rates for ages above 80 Age groups with heart rates below 220 Possible heart rates for ages above 40