1. To solve the formula for A, the first thing we are going to do is subtract M for both sides of the equation: Next, we are going to add 0.8A to both sides of the equation: Finally, we are going to divide both sides of the equation by 0.8:
2. Now, to find at what age
the maximum heart rate in beats per minute should be 140, we are
going to replace M with 140 in our formula:
We can conclude that 45 years old person, must not exceed a heart rate of 140 beats per minute during exercise.