When you need to round a number. First you need to look at the placement number that the question is asking to round to the nearest.
In this case it's the nearest tenths.
.8 is in the tenths place.
Now look to the number to the right of that number 3 that's the number that tells you if you will round up or down.
If the number is 5 or more you round up, if it's less than 5 you round down.
In this case the 3 is less than 5 so you round down.
So your answer would be 8.8
Hope this helps.