Answer :
[tex]100\%-20\%=80\%\\\\80\%\cdot50=\\\\0.8\cdot50=40\\\\A\ boat\ cost\ \$40\ after\ sale.[/tex]
Original price was $50 x 0.20 = 10
Original price $50 - 10 = $40 the sale price before sales tax
Original price $50 - 10 = $40 the sale price before sales tax