Chapter 1 - Equations and Inequalities - 1.2 Applications and Modeling with Linear Equations - 1.2 Exercises - Page 100: 6

Option $D$

Let x = original price Note that $60\%=0.60$. A $60\%$ discount means 60 percent of the original price is deducted from the original price itself. Thus, in mathematical sentence, a 60-percent discount is represented by: $x-60\%x = x - 0.60x = 0.40x$ Since $0.4 = \dfrac{4}{10}$. then the discounted price is also equivalent to $\dfrac{4}{10}x$. Therefore, the one in Option D does not represent the discounted/sale price.