Question

Mary bought a book that cost $18 at a diascount of 16% . what did she pay for the book

Answer 1

`x-the \ price \\ \\ 16 \% \ of \ x= (16)/(100)*x= (4)/(25)* x =(4x)/(25)-\ the \ discount \\ \\ x^((25)-(4x)/(25)=(25x-4x)/(25)=(21x)/(25)- \ the \ new \ price \\ \\ (21x)/(25)=18 \\ \\ x=(25*18)/(21) =(450)/(21) \\ \\ \boxed{x=21.42 \$}`