Advanced interaction

I have attached the slide I am working on. I am not sure if this is even possible, but if so I would love to learn from someone.  In this interaction, the learner will plan a day at an event. I would like to have a box that will keep track of how many minutes they are spending per session. For example, if they choose "lecture" it will add 60 minutes to the "time box" and if they then choose "break" it will add 30 minutes to the current time of minutes in the "time box." Keeping track of the total amount of time used as they choose each session.