He wrote down a simple thing -- so simple, in fact, that I suspect a really smart high-school student who didn't even have calculus could understand what he wrote down.
정말로 굉장히 단순했어요. 제 생각에 미적분학을 배우지 않았더라도 꽤 똑똑한 고등학생이라면 그가 쓴 내용을 이해할 수 있었을 겁니다.