If mario started his homework at 3: 30, and then finished 25 minutes later what time did he finish?

Ok, since the minutes here are 30, all we need to do is simply add 25 minutes to our time.

3:30

Now 30 + 25= 55

So our final time he finished: 3:55

If you would like to know what time did Mario finish his homework, you can calculate this using the following step:

3 (hours) : 30 (minutes)  + 25 minutes ... 3 (hours) : (30+25) (minutes) ... 3 (hours) : 55 (minutes) ... 3:55

The correct result would be 3:55.