Question

The journey aroundthe world took the old sailor nine months,(of which)the sailing time was 226days

为什么选of which

Answer 1

which指代nine month，全句意思：环球航行花了老水手九个月时间，其中航行时间为226天。

Answer 2

这句是几年前的高考题。先告诉你含义：
环球旅行花了这水手9个月【270天】，其中航海时间为226天。
即还有40多天不在航海，可能用于维修船只，休息等。
The journey around the world took the old sailor nine months,226days of the nine months was sailing...