The first step is to find an average for all of the data obtain. This is because the data should be an average number from all participants, using only data from individual would not be suitable.
After the average data is calculated you will have the following data.
Symbol “A” count number “20 ((20+20)/2)” time 57 ((60+54)/2) seconds
Symbol “B” count number “35.5” ((37+34)/2) time 26.5 ((25+28)/2) seconds
After this stage, you already obtain the value for the time on task (time taken for counting each symbol).