A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 42.9 kpa. what is the partial pressure of carbon dioxide if the partial pressure of oxygen is 6.6 kpa and the partial pressure of nitrogen is 23.0 kpa?
a. 29.6 kpa
b. 19.9 kpa
c. 13.3 kpa
d. 36.3 kpa
e. 14.3 kpa