Eric has been donating books he no longer needs to his local library. After 3 months of donating, he had 157 books left in his room. After 8 months of donating, he had 102 books left in his room. How many books per month did Eric donate on average between months 3 and 8?

Question

anonymous · Answer

-31 books per month

 -18 books per month

 -11 books per month

 -7 books per month

calculusxy · Answer

First let's find the time difference of 8 months to 3 months. That will be 5 months. 

Now, let's subtract 157-102=55 (that is how many books he has decreased from 8 months all the way to 3 months). To find the average, we need to divide 55 by 5, which will equal to 11. 

So I would say that the answer is -11 books per month.

calculusxy · Answer

@sumsumjoe