It would be 7.8.
If we are rounding to one decimal place, it would mean to be rounding to the .7's place, so we look to .06 to see if it's larger or smaller than 0.5. It is! So we should round .7 up instead of keeping it the same, bringing us to .8. Then you add the 7 to it and you get 7.8.
Hope this helps! :)