Answer: 36 min/day
Of the 300 min/week allocated to spend on screens, 84 min has been already spent for the current week, which means that 216 min is left:
300 min - 84 min = 216 min
Of the 216 min left, it can be split evenly between 6 days if 36 min is spent each day on screens:
216 min ÷ 6 days = 36 min/day
∴ they can spend 36 min on their screens each day.
