21/1.5=14
14 years to erode
Answer:
2/15
Step-by-step explanation:
Given that she have already read one-third of the book.
The fraction f of the book that will remain is;
f = 1 - 1/3 = 2/3
Then she finishes the book by reading the same amount each night for 5 nights
That implies she reads the remaining 2/3 of the book at equal rates for 5 nights.
Let x represent the fraction rate read per night;
5x = 2/3
Divide both sides by 5
x = 2/3 × 1/5
x = 2/15
Therefore, she reads 2/15 of the book every night for 5 nights.
Hope the image below helps :)
