Asurvey of 1,000 people was done by new york times. 80% of the people did not know the name of their representative in congress. how many of the 1,000 people knew the name of the congressman?

Okay, so how I solve this answer is by first figuring out how many people didn't know the name.

So, If 80% of 1,000 didn't know the name that means 800 people did not know the name.
                   (1000 x .8 = 800)

Then you take the total number of people, 1000, minus the people who did not know the name, 800, and you get the total number of people who did know the name which is; 
                   (1000-800=200)

200 people knew the name of the congressman.