Final answer:
Mrs. Johnson bought 8 books.
Step-by-step explanation:
To find out how many books Mrs. Johnson bought, we need to subtract the amount she spent on magazines from the total bill.
Mrs. Johnson spent $16 on magazines, so the remaining amount is:
112 - $16 = $96.
Each book costs $12, so we divide the remaining amount by the cost of each book:
$96 / $12
= 8 books.
Therefore, Mrs. Johnson bought 8 books.