Answer:
5 books - 27 days
10 - 54 days
15 books - 81 days
Step-by-step explanation:
First, you need to find how many days it takes to read one book, to do this, simply divide 135 by 25 (135/5=5.4). Then, you multiply that number by the amount of books it wants to know how long it would take him to read (5 and 15 since it asks "another 10". It could also be 54 if it was asking how many for 10 books not including the 5 he would have read). 5*5.4=27, 10*5.4=54, and 15*5.4=81.
