From the context, it looks like she encoded a future moment in time.
If you still don’t know the letter, your brain’s running lower than a Monday morning without coffee. And if the number’s still a mystery to you, go ask some kid in third grade. That’s about the time they learn division.
The correct answer is “S7”, meaning Sunday at 7 p.m. The first sequence represents the days of the week, and the second is a pattern of dividing the previous number by two.
