Among the 1013 respondents, 407 said that pesticides are "not at all annoying". What percentage of respondents said pesticides are "not at all annoying"?

You take the number of respondents who said pesticides are "not at all annoying" and divide it by the number of total respondents. So you would divide 407 by 1013 (407/1013) then multiply what you get by 100. You get 40%