Answer:
Option 4: 10d + 5
Explanation:
Given the algebraic expression, 5(2d + 1), which represents the fines per day, d, for overdue books.
In order to determine the equivalent algebraic expression of 5(2d + 1), we must distribute 5 into the terms inside the parenthesis:
5(2d + 1)
= 5(2d) + 5(1)

Therefore, the equivalent expression is: 10d + 5.