Question

Catherine paid $185.30 for an MP3 player. If the price paid includes a 9% sales tax, which of the following equations can be used to determine the price of the MP3 Player before tax? (Let x represent the cost of the MP3 player and y represent the total cost after tax.)

Answer 1

y = $185.30

x = the orignal cost minus 9% or .09. To increase an objects value by 9% you need to multiply by 1 + .09 or 1.09. So, x being increases by 9% would equal y or $185.30

1.09x = y

1.09x = $185.30

Divide both sides by 1.09

x = $170