Not sure if i understand but can someone help me understand by what its means of the problem?

Answer:
Variable: b
Equation: $12b + $16 = $112
Solution: 8 books
Step-by-step explanation:
$12b + $16 = $112
$12b + $16 - $16 = $112 - $16
$12b = $96
$12b ÷ $12 = $96 ÷ $12
b = 8
Hope that helps.