During exercise the recommended maximum heart rate in beats per minute is modeled by the formula M=176 - 0.8A, Where M is the Maximum heart rate and A is the persons age approximately, at what age would you have a recommended heart rate in beats per minute of 125?

52 years

64 years

67 years

70 years

Since 125 represents a maximum heart rate (which has been generally defined as M), you must plug 125 into the equation to get 125 = 176-0.8A. You can solve it from here by subtracting 176 from both sides to get - 51 = - 0.8A, then dividing both sides by - 0.8 to get A = 63.75. You can then round (it says approximately) to A = 64 as your final answer (Option 2).