Answer:
20bpm
Step-by-step explanation:
To determine who will be in their target heart rate (THR) zone after decreasing their heart rate by 20bpm, we need to subtract 20 from their current heart rate of 173bpm.
For Devon, 173bpm - 20bpm = 153bpm.
Since Devon's target heart rate zone is 140bpm—p177bpm, and 153bpm is within that range, Devon will still be in his THR zone after decreasing his heart rate by 20bpm.
For Julian, 173bpm - 20bpm = 153bpm.
Since Julian's target heart rate zone is 148bpm—181bpm, and 153bpm is within that range, Julian will still be in his THR zone after decreasing his heart rate by 20bpm.
Therefore, both Devon and Julian will still be in their target heart rate zones after decreasing their heart rates by 20bpm.