lt has been calculated that the Earth's circumference around the equator is more than forty longer miles than that

around the two poles.

어순이 제대로 되려면 forty longer miles 를 forty miles longer로 해야 된다고 하셨는데

the equator is more than 에서 more than을 빼야하지 않나요?

정리하자면 the equator is forty miles longer than ~~

more than longer than 이렇게 두번 비교급이 들어가야 하는 이유가 있나요?