Answer:
32 days
Step-by-step explanation:
make a rate time distance chart:
r t d
first 5 | y | 5 | 5y
final days | y+6 | x-6 | (y+6)(x-6)
take y for planned rate and x for time till test
then make system of equations:
1. 5y+(y+6)(x-6) = 844
2. 768/y =x
/Henrietta knew the time till test, so we can assume that she planned in such a way that would mean she learned exactly 768 spells if she worked at the set rate. On this assumption we make 2
solve, and you get 2 options: x=-10/3 y =-144 (exclude, negative)
the second one is x=24 y=32 that works for us, so answer is she planned to learn 32 spells each day.