Answer:
 A) Seattle's sales were 40.42% larger than Portland's. 
 B) Portland sales were 28.79% smaller than Seattle's. 
C) Portland sales were 71.21% of Seattle's.
Explanation:
Since a company's sales in Seattle were $ 330,000 in 2012, while their sales in Portland were $ 235,000 for the same year, the following calculations must be performed to complete the sentences: 
 
A) 
 235,000 = 100 
330,000 = X 
330,000 x 100 / 235,000 = X 
33,000,000 / 235,000 = X 
140.42 = X 
 
Seattle's sales were 40.42% larger than Portland's. 
 
B) 
 330,000 = 100 
235,000 = X 
235,000 x 100 / 330,000 = X 
23,500,000 / 330,000 = X 
71.21 = X 
100 - 71.21 = 28.79 
 
Portland sales were 28.79% smaller than Seattle's. 
 
C) 
 330,000 = 100 
235,000 = X 
235,000 x 100 / 330,000 = X 
23,500,000 / 330,000 = X 
71.21 = X 
 
Portland sales were 71.21% of Seattle's.