Giving feedback to participants by counting answers matching predetermined value

I am very new to Qualtrics and working on a survey for my Bachelor´s Thesis.
It´s a memory task. I have 30 pictures and names shown to the participants with loop & merge. Their task is to memorize those pictures. Afterwards they are shown the old 30 pictures and additionaly 30 new ones (in a randomized order). They are asked to select whether it is an old or a new picture by pressing the corresponding button.
My goal is to give the participants feedback on how well they performed by counting how often they pressed the right button (old/new). In order to do that I added an additional coloumn to the loop & merge indicating whether the picture is old or new. My idea was to count how often the participants answer matches the value in this added coloumn. Is this a possible way to count the right answers and if so, how can I implement this in Qualtrics? Can I create a variable to achieve this?
Thank you in advance!