Final answer:
The 'rule of nines' is used to estimate the percentage of body surface area that has been burned. In this case, the chest, abdomen, back, buttocks, and right arm are all affected, representing a total of 45%.
Step-by-step explanation:
The 'rule of nines' is used to estimate the percentage of body surface area that has been burned. According to this rule, specific parts of the body are associated with a percentage of body area that is a factor of nine. In this case, the chest, abdomen, back, buttocks, and right arm are all affected. Each of these areas represents 9% of the total body surface area. Therefore, the total percentage of body surface area burned would be 9% + 9% + 9% + 9% + 9% = 45%.