This phrase "te wo furu hito ni egao de kotae" is translated as "Smiling back to the people who waves their hands"
"te wo furu hito ni" I suppose it's "to the people who waves their hands" , kotae is "to respond" and "egao" is "smile". Then why it's "egao de kotae" and not "egao o kotae" . With "egao de kotae" isnt it trying to say "respond a smile" or the literal translation would be another? Does this verb simply work with "de" instead of "o" or is there any other explanation and I'm getting it all wrong?