please help me ill give brainist to those who give me a reall answer (helpless answer not allow)

Answer:
Here:
Step-by-step explanation:
1.
Demand tipped
6.44$
The Total bill came out to be
38.64
EXPLAINATION:
20% of $32.20 is $6.44
2.
Barnes & Nobel's
$13.25
Amazon
$14.55
$13.25 * 15 = $198.75 - Barnes
$14.55 * 15 = $218.25 - Amazon
Answer
You will save 19.50 dollars if you buy the books at Barnes & Nobel's.