Answer:
C) 29; yes or D) 29; yes
Explanation:
At $60 per massage, Tracey is willing to supply 8 massages, Kira is willing to supply 15 massages and Peter is willing to supply 6 massages, so in total they are willing to supply 29 massages.
This supply schedule follows the law of supply because the total quantity supplied increases as the price per massage increases: 18 at $40, 29 at $60 and 42 at $80.