Taking the time to be 8:21, and subtracting 30 minutes, gives 7:51.
Convert everything to a common unit (I suggest to convert to hours in this case, but minutes will do, too), then you can subtract.
To find the answer, subtract 9:30 from 11:40. The answer is 2 hours and 10 minutes.
Convert 20 minutes into seconds (20 * 60). There are sixty seconds in a minute. This would make 1200 seconds. Then add the 45 seconds (1245). Convert 30 minutes (1/2 an hour) into seconds (30 * 60). Then subtract 1245 from 1800. This would leave 555 seconds or 9 minutes, 15 seconds. I hope this helps.
410.5
5
8 hours 5 minutes.
7 hours 45 minutes.
Convert everything to a common unit (I suggest to convert to hours in this case, but minutes will do, too), then you can subtract.
9 to 5 is 8 hours. If you subtract the lunch break, you get 7 hours, 30 minutes.
To find the answer, subtract 9:30 from 11:40. The answer is 2 hours and 10 minutes.
30
821 x 1 = 821
Convert 20 minutes into seconds (20 * 60). There are sixty seconds in a minute. This would make 1200 seconds. Then add the 45 seconds (1245). Convert 30 minutes (1/2 an hour) into seconds (30 * 60). Then subtract 1245 from 1800. This would leave 555 seconds or 9 minutes, 15 seconds. I hope this helps.
13 hours 41 minutes.
you would change hours to minutes. 1 hour=60 minutes
subtract Example: $5 off $30 is $25
50% of 821 is 410.5