The original price of the book shall be represented by x.
The book was sold at a price of $16, which is 20% off its original.
This means x is 100%, while 16 is 80%. Therefore;
[tex]\begin{gathered} \text{Original cost can be }\det er\min ed\text{ by the equation;} \\ \frac{80}{100}=\frac{16}{x} \\ \text{Cross multiply and you have,} \\ x=\frac{100\times16}{80} \\ x=20 \end{gathered}[/tex]Therefore, the original price is $20
The correct answer is option D
