A man has a job which requires him to work 8 straight days and rest on the ninth day. If he started work on a Monday, the 12th time he rests will be on what day of the week?

For the man to take $$12^{th}$$ time rest he has to work for $$\left(12\times\ 8\right)=96$$ days and have rest for 11 days

Total days lapsed will be 96+11 = 107 and hence the $$12^{th}$$ rest day is $$108^{th}$$ day.

Day 1 is monday. After this Day 8 will be Monday. In general $$\left(7k+1\right)^{th}$$ day is Monday

Therefore $$106^{th}$$ day is Monday. $$108^{th}$$ day or $$12^{th}$$ rest day will be Wednesday