Answer:
The net profit rate on the book is 5.41
Step-by-step explanation:
Given as :
The marks up percentage of book = m = 40%
The overhead rate is 16% of selling price
The cost price of book = c.p = $18.10
Let The profit = $p
Let The selling price = s.p
<u>Now, According to question</u>
mark up percentage = 
I.e 40% = 
Or,
+ 1 = 
Or,
= 
Or, s. p = 
∴ s.p = $25.34
So, selling price of book = s.p = $25.34
Now, The overhead percentage = 16%
i.e overhead rate = 
Or, estimated cost = 16% × 25.34
I,e estimated cost = 0.16 × 25.34
∴ estimated cost = $4.05
Now,
Profit = selling price of book - estimated book cost
I.e p = $25.34 - $4.05
∴ p = $21.29
So, The profit rate% = 
I.e The profit rate% = 
∴ profit rate %= 5.41
So, The profit rate = p = 5.41
Hence, The net profit rate on the book is 5.41 Answer