Huh?No, you do not add up all the frequencies. One reason is that you can't since the frequencies are not even given. You do however do just what you did and add up the values in the row labeled Tally
Regardless of what frequency means there are no values listed under frequency in the table.Huh?
The frequencies are determined by counting the tallies (as the OP did, carrying out part a), and then you add those up for part d.
Are you thinking that "frequency" means something else?