Bob finished baking cookies at 10:51 a.m. He started at 6:29 a.m.

How long was he baking cookies?

To find out how long Bob was baking cookies, we must calculate the difference between his finish time and his start time.

First, calculate the minutes difference:
Finish time: 10:51 a.m. = 10*60 + 51 = 651 minutes
Start time: 6:29 a.m. = 6*60 + 29 = 389 minutes

Next, calculate the total baking time:
Total baking time = Finish time - Start time
Total baking time = 651 minutes - 389 minutes
Total baking time = 262 minutes

Therefore, Bob was baking cookies for 262 minutes.