Joe is learning to play the trumpet. on monday he practiced from 6: 30 until 7: 05.on tuesday he practiced from 3: 55 until 4: 15. how many minutes did he practice in all over the two days.?

Let's start with day 1:

We know that Joe practiced from 6:30 to 7:05
An hour is 60 minutes
Joe practiced for the 30 minutes left in that hour and 5 minutes into the next

30+5=35

So, he was playing for 35 minutes on the first day

Now, we can do the same thing for the second day:

He started at 3:55 and ended at 4:15
An hour is 60 minutes
Joe practiced for the 5 minutes left in the hour and the first 15 minutes of the next hour

5+15=20

Now we want to add the number of minutes he practiced for both days

35+20=55 minutes

No because if you do the higher number minus the lower number you will get a positive. if you do it the other way around you will get a negative number