To round 8 hours and 35 minutes to the nearest quarter hour, you need to look at the number of minutes.
Since 35 minutes is closer to 30 minutes (a multiple of 15) than it is to 45 minutes, you would round down to the nearest quarter hour.
Therefore, 8 hours and 35 minutes rounded to the nearest quarter hour is 8 hours and 30 minutes.
I hope this helps.