Answer:
8 7/10 - 3 4/10 = 5.3, 5 3/10, or 53/10
5.3, 5 3/10, and 53/10 all equals to 8 7/10 - 3 4/10 :)
Step-by-step explanation:
The position of the fly is shown as cross in the diagram below
The distance of the fly from the ceiling is given as
We need to work out the distance

to be able to work out the value of

by the Pythagoras theorem



by Pythagoras theorem


The distance of the fly from the point P is 4m
After the first day, 1/3 of the original amount remained:
... (1/3)·45 = 15
After the second day, 2/3 of that amount remained:
... (2/3)·15 = 10
The bookstore has 10 copies left.