If they have been generated by means of the Data | Subtotals routine,
then you can group and ungroup rows using the symbols in the panel on
the left.
If instead they have been manually generated by inserting rows at the
appropriate point, then these rows can be selected by means of an
Autofilter on a column which does not have the formulae - selecting
<blanks> as the criteria. Note that the subtotals will show 0 if this
method is used, but if you only want to format the visible rows this
does not matter.
Hope this helps.
Pete