During exercise, the recommended maximum heart rate is modeled by the formula, M = 176 – 0.8A, where M is the maximum heart rate and A is the person’s age. At what age would you have a recommended maximum heart rate in beats per minute of 140?

Starting with the formula M = 176 – 0.8A, we can set M equal to 140 and solve for A.

140 = 176 – 0.8A

Subtracting 176 from both sides:

-36 = -0.8A

Dividing both sides by -0.8:

45 = A

Therefore, at age 45, a person would have a recommended maximum heart rate of 140 beats per minute during exercise.