Jacob traveled from Nakuru to Mombasa. He started his journey at 8:35 am and arrived at 5:15 pm. How long did his journey take?

Jacob started his journey at 8:35 am.
He arrived in Mombasa at 5:15. Assuming this is 5:15 pm on the same day, as a journey from Nakuru to Mombasa typically takes several hours and would span past noon.

From 8:35 am to 9:00 am: $60 - 35 = 25$ minutes.
From 9:00 am to 12:00 pm: $12 - 9 = 3$ hours.
So, the duration from 8:35 am to 12:00 pm is 3 hours and 25 minutes.

From 12:00 pm to 5:15 pm: 5 hours and 15 minutes.

Total hours = $3 \text{ hours} + 5 \text{ hours} = 8 \text{ hours}$.
Total minutes = $25 \text{ minutes} + 15 \text{ minutes} = 40 \text{ minutes}$.

The total travel time is 8 hours and 40 minutes.