Ashley's thr zone is 146bpm - 181bpm. jonelle's thr zone is 151bpm - 184bpm. they stop dancing and take their pulse and both count their heart rate at 155bpm. if they increase their heart rates by 20bpm, who will be in her thr zone?

155bpm + 20bpm = 175bpm.
Both Ashley and Jonelle will still be in their THR zone. 
Ashley's 175bpm is still within the 146bpm - 181bpm THR zone.
Jonelle's 175bpm is also still within the 151bpm - 184bpm THR zone.
Ashley's 155bpm can be added a maximum of 26bpm to still remain within her THR zone while Jonelle's 155bpm can be added a maximum of 29bpm to still remain within his THR zone. Beyond those numbers, their heart rates will exceed their THR zones.