It's a good idea to draw a picture with word problems.
1) Draw 8 cups with 3 tics on them dividing the cups into fourths
2) Shade up until the 3rd tic on the first cup. That's one day.
3) Shade the last section of the first cup and the first 2 sections of the second cup. Marking a second day.
4) Repeat this until every full day has been shaded in. (You'll find that 3 cups equal four days)
5) This leaves you with 11 full days and 3/4 of a day.
Answer= 11 3/4 days (11 days and 18 hours)
I hope this helped!